Don't make a thread with your question as the OP because we all know you do it so people might answer your question - edition.
Ask questions here like
>silly HW questions
>concepts or things you might not understand
>dumb little short questions that probably wouldn't be a good OP but still worth asking
Explain the Lorentz transformations to a retard please. I only got the [math](t_{2}-t_{1})^2 - (x_{2}-x_{1})^2 - (y_{2}-y_{1})^2 - (z_{2}-z_{1})^2 = 0[/math] part, and the time dilation via multiplication by the Lorentz factor. I don't get the rest.
>>7997278
Since you don't measure absolute velocities, only velocities relative to your reference frame, you need a way of transforming between the different frame's. Otherwise you'd end up in the bizarre situation where physics was affected by the velocity of your frame. Classically we the Galilean transformation (which if you've never heard of before might help you). When we get to relativistic velocities we find the Galilean transformation no linger works (it predicts that the speed of light should be dependent on the frame velocity when we know from both theory and experiment that it's a constant in all frames). So we need a relativistic generalisation of the classical transform, that lead's us to the Lorentz transformation. Better?
>>7997295
I get that, but what I don't get is the math behind the transformations, and how to get from the classical Galilean transformation to a relativistic one.
somebody explain like I'm 12 the fundamental theorem of calculus
>>7997315
>I don't get is the math behind the transformations
What don't you get?
>how to get from the classical Galilean transformation to a relativistic one.
Well here's the thing, you don't go from classical to relativistic. Part of its derivation includes an appeal to the "correspondence principal" which means that at low velocities you return the classical transform. Einstein's original paper is called "On the electrodynamics of moving bodies" you might gain something by reading it.
>>7997330
The integral of f from a to b is the same as the antiderivative of f at b minus the antiderivative at a
>>7997334
Doesn't really explain anything about the fundamental theorem of calculus. What is the idea/theory behind it? I know how to evaluate a definite integral already.
>>7997332
The part that I don't get is how to get from general linear transformations to Lorentz transformations.
>>7997343
Have you constructed an integral via riemann, darboux, Stieltjes or lebesgue?
>>7997348
I know Riemann.
>>7997330
average rate of change × interval = area
>>7997343
Basically, an integral between two points of a function is the net area under the curve of that function. That is, the area above the curve minus the area under the curve. This area represents the net change of the value of the function between these two points.
The value of the function will depend on the net change. The more the net change is, the higher the value.
This is as "intuitive" as I can get. You should probably watch a video by KhanAcademy, he explains it better.
>>7997353
Well thats the FTC. That the inverse of the derivative is the integral and vice versa.
Slopes and areas dude. They're related
Is IQ meaningful? And could someone link studies supporting their answer?
>>7997343
The general idea is this - final minus initial.
Now i know you might be thinking "well duh" but you kinda gotta look at a proof of it to understand. That is what I would recommend first.
The general idea is this though - let's consider an integration over this region from 0. We know that base times height gives us the area of it. So since it starts from the origin, we can do that calculation pretty easily.
Now consider a triangle. We know the equation for that. But what if it didn't start at the origin? Well we could still find the base measurement by taking the final x coordinate minus the initial x coordinate.
Well as it turns out, integration is the same as finding the area of a surface. That's what the FTC is capitalizing on - you can simplify almost any figure into a base times height problem.
Now what goes on in the background of this is KIND OF black magic and I admit it myself. But I think a triangle is a pretty good way to see what is happening. Take a function x, which is the slope of a triangle. (duh) the integral of that is what we recognize as the area of the triangle. We know that works obviously and we talked about the final minus initial method for the measurements. Right? You'll find that if you just keep coming up with functions that have a shape, integrating over them gives you the simple area equation you know and love. (go ahead and see if you want)
So, it's what happens in between that is black magic. It turns out that when you do this, you are taking an infinite amount of slivers underneath your function, and when you take final minus initial, math (again, you need to look up a proof for this I imagine) works in a way that you are taking all those slivers and adding the area of said slivers to get an area. It's kind of neat.
Don't know if this helps since I don't know why you are hung up on it, but
>>7997330
If f(t) is distance at time t, f'(t) is velocity at time t.
At small time intervals I, [math] f'(t)|I|[/math] is roughly the distance you cover in the interval I.
If you chop the interval [a,b] into infinite infinitesimally small subintervals [math] I_k[/math] and sum you get the total distance covered [math] f(b)-f(a)[/math]
What are some good physics resources to learn? I'm taking calculus based physics 1 right now, and its not too bad but I feel like I could be learning it much better. I was not impressed with the Khan Academy videos
Just stepped outside, and I got hit by the strong scent of rotten eggs. Can't figure out where it's coming from, could it have anything to do with the thunderstorm outside?
>>7997346
Like the other guy said, you don't go from a simple linear transform to a Lorentz transform. The Lorentz transform is gained from a ground up derivation with extra conditions. The regular Galilean transform is an approximation of the Lorentz transform at velocities much lower than c.
Anyone? >>7997366
>>7997629
It's a good indicator of how good you are at IQ tests
Working on practice exams for a diffy exam I have, and something came up that has me a little bothered.
"For what range of b will the solution to the differential equation oscillate indefinitely?
y'' - by' +(2b - 3)y = 0
I was under the impression that since this is a damped system, it would never oscillate indefinitely, but solutions list it as the range from 2 to 6. (IE, the range of which underdamped motion)
Do I not have this correct? Or is something botched? If it's underdamped motion, shouldn't it just gradually decrease to zero?
>>7997330
The idea is that you have some function, say x^2
You'd like to know the area of x^2 for whatever reason. You pick two arbitrary points on the function, say from 0 - 1. From here you take the anti derivative of the function so (x^3)/3 +C and plug in your values so you get 1/3 - 0.
To make it even simpler think of final - initial.
>>7997534
Ozone
>>7997244
So if I write a program what exactly is happening on the hardware? Are the circuits just opening in closing in a specific fashion?
I remember when I took comp sci 101 they told me that the compiler makes the program as small as possible, sends the instructions to the CPU and then executes them in the order it was sent.
I don't get how to add / subtract trig functions.
How would you do this for example:
csc 30° - cos 45°
Really dumb question,
But determining "if a is a primitive root modulo m"
means just checking if it is a primitive root right?
Eff man came from monkeys, y r their still munkeys?
>>7998013
Imagine a lighthouse overlooking a bay and a ship out at the sea. The ship is trying to navigate, and the operator of the lighthouse sits inside the lighthouse. The operator is at his desk on his computer, using a computer, which runs programs. That's how computers run programs.
>>7998060
Use trigonometry
>>7998275
I don't know
>>7998286
Because the set containing the zero vector has dimension zero
>>7998060
Switch to rational trig and then just substitute and solve
>>7998013
I took a great class called digital design that explained how to get from logic gates to basic computers.
Then all you need is to understand assembly and you'll have a decent understanding down to the transistor level.
I wish I could tell you more but I'd have to reread the book
>>7997534
Rotten eggs smell is hydrogen sulfide.
common sources are volcanic springs, flatulance and rotten eggs, but Ive had water that had the taste.
I have no idea why it could come from rain, unless you have acid rain coming down and it somehow broke down.
The only sulfuric acid I've smelled smelled like burning nose.
>>7998011
Ozone smells like sparks
>>7997931
Effectively it damps out, but technically it keeps overshooting the final value for all eternity.
In control theory we use something called a settling time where we see how long it takes to get to a percentage of that final value (usually 98% iirc) and the only system that would oscillate forever is the undamped one.
I'm not very smart and I can't figure out how to word it properly on google to get the results, but something that's always bothered me is that on one hand, people bring up that we can't see past the edge of the observable universe, but on the other hand, people say that we can see the beginning of the universe.
How exactly does that work? How can we see both the end of the observable universe(the point which we can't see any further) and also the beginning?
>>7998475
The end of the universe is the beginning!!
Now for the less fun stuff:
Light takes time to travel to us, so we can see in the past by looking out at something at a distance.
Farther we look, earlier in the past.
The observable universe is everything we can see (duh) so theres no possibility of seeing past it. Since its the furthest part it must be the oldest.
The reason we can't see past the edge of the observable universe is because there was no before it. So there's no photons that have reached us from past that boundary
Bonus: things are expanding away at a faster and faster rate. If a point is expanding away from us at a speed over the speed of light, there's no way for it to interact with us.
>>7997931
Use the determinant after y=e^Mt
Any range of b greater than 0 oscillates indefinitely
>>7997244
I'm not understanding what this question asks me so if any of you could help my deconstruct it that would be great.
Background info: Deep space probes such as Voyager, are powered by “thermionic” devices which convert the heat from radioactive decay directly into electrical energy. The typical radioisotopes used is 238 Pu 94 which decays via alpha emission to 234 U 92.
Pu-238 = 238.0495 u U-234 = 234.0409 u He-4 = 4.0026 u
The question is: If all the energy comes from the kinetic energy of the alpha decay, calculate the number of decays in 1 second, if the activity of the Plutonium is 1.45 x 10 14 Bq.
This is my answer to one of the dumb ass questions on OKCupid. Did I do alright?
>>7998543
This is pretty simple and I'd hope the average person could understand it. Not sure if this was an attempt at "bragging", but this seems incredibly autistic that you would even do that.
>>7998548
The main reason I did it is because I am in Sequences and Series calculus right now and was working on homework with these exact types of problems.
So yes I am partially bragging and also displaying my autism for all to see to see if it attracts any ladies
Would it be possible to create a formula, that can solve every math problem by having variables that have a value belonging just to the problem you are about to solve?
Anyone has a good guide on how to design a tube and shell heat exchanger? I'm interested in reviewing how to design one.
>>7998862
you can do back of the napkin design with just an undergraduate heat transfer text. however you would probably have to adjust final flow rates.
if you want some on-the-nuts design, your gonna have to fire up Solidworks or Fluent and do a simulation.
If t=x/(x+1), why is (x+1)/x=1/t?
Good purchase?
>>7999417
Only bought the quick calculus shit because I need to be able to solve baby calculus problems easily for now, after I take that exam I will study calculus profoundly from a real book.
Also, studying number theory from Serge Lang's basic math.
Given a 90% confidence interval, how do I find the sample standard deviation? I'm not given n, so I'm not sure how to go about this.
>>7999427
Okay so I divided the two bounds by each other so I got the ratios of the chi-squared values, each of df n-1. I suppose I'm meant to test out different ratios from my table corresponding to the 90% interval until I find this particular one.
>>7999450
Well that ended up working after a few tries, thanks /sci/
>>7997244
Are there any good resources that could teach me how to determine the solubility of elements or compounds in molten metals versus solid state metal?
I want to understand Zone Refining better.
I'm sorry for being so stupid, but why does
[math]r_a -r_b[/math] being a multiple of m implies that [math]-m<r_a-r_b<m[/math] here?
>>7999652
Because if I'm interpreting the image correctly, then this is part of a demonstration of some division/Euclidian algorithm, or similar which I should know OTTOMH but don't. In other words, each individual letter-form stands for some natural number, and since thingy is a multiple of m, oh dear now I've gone cross-eyed and and the things contradict my above assumptions.
So we really need more context. In fact, we need the context of the larger train of thought to make sense of this. It's obviously moving along toward some other step, but we don't know what. Given my above assumptions, perhaps a (proof by) contradiction is in the offing, but again we don't know without more information.
The "OTOH" clause suggests that the author is aware of putting two conflicting pieces of information side-by-side, which goes to my above supposition.
>>7999685
Oh damn, I seriously am retarded, I didn't even think about that. Here's the context.
I'm really sorry, I'm trying to understand this proof through.
Why do roboticists insist on building fuck-ugly rubber zombies that no one without autism could ever find beautiful, elegant, attractive, or aesthetically pleasing?
>>7999734
They're desperate for investors and they don't think they can get any with faggy cartoon shit
>>7999702
If you look at the first page, 0<=ra<m and 0<=rb<m. ra and rb are both positive and less than m, so think about it. if ra>rb then ra-rb will be positive (but still less then m because they are both less than m). if rb>ra then ra-rb is a negative number but for the same reason as before its gonna be larger than -m. I didn't read the whole proof, I'm just answering your original question.
>>7999754
Wow, that was really helpful. I get it know, my question was answered. Thanks a lot.
>>7999744
Because nasty uncanny valley monsters are working SO well for them.
>>7999702
And so my above assumptions were mostly correct (division argument and only integers) and the author is not driving toward a contradiction as such, but rather a simple forcing that "thingy" can only be equal to zero, which [he] then uses to establish his other thingy (his theorem, which I would instead call a lemma, doesn't matter).
Because both "r" remainders are manifestly natural numbers. And their difference is T, or "thingy". Maybe T is even a negative number, for all I know. But it definitely isn't greater than or equal to m. Because neither one is. If you were adding the two, it might be a different story. But we're not, so it isn't.
The one train thought shows that m | T. That is, m divides T. T is a multiple of m. But also, since neither one of the remainders is equal to or greater than m (which is just a natural number) then no matter how you slice it, T is strictly less than m.
So we have two conditions, where m is some natural number (inclusive of zero, read the above), and T is some integer (maybe it's negative!). The two conditions are, that
T < m
and there exists some other integer U such that
Um = T
All three of those things are integers, when you really look at it, there's just a restriction on m. If m is zero, then T is zero. And we don't care what integer U is, it could be anything. And if m is one, then U = T < 1. So T is AT MOST equal to zero, but along my alternate route, I hold open the possibility that T is some negative number.
How about when m is two, or anything greater? Well then it gets multiplied by some other integer and it ends up being less than m (since T < m). And the only way for that to happen, is if U is non-positive.
The point is that in one case I thought about (the cases here, are the choices of m), T was forced to be zero, and nothing else. And in the other two cases, zero remains open as a possibility. I leave the rest to you as an exercise to understand (hint: -m is a lower bound, too)
Can someone explain to me what the flaw in this logic is? I know it can't be correct, right?
>>7999849
Because there's no such thing as a square root of a negative number, unless it's an imaginary number. And then, it becomes an entirely different story.
In other words, learn what imaginary numbers are.
>>7999856
I'm not super great at math, but I know what imaginary numbers are, and when shown the problem I just did (2i)(3i) = -6
I was shown this solution and I don't understand why doing it this way is flawed.
>>7999744
the VR goggles seem to be taking care of the faggy cartoon shit for the moment. Or what amounts to the same thing, hentai on the internet.
What books are considered to be Math Classics/Must reads? Books like, for instance, Principia Mathematica or Elements by Euclid? If possible, what order to read them?
>>7999862
When you took the square root in step 4, you introduced the possibility of two solutions to the intermediate equation 36 = x^2. Because you've been taught to do this by rote when taking a square root.
But in your first line, you had specified that x has exactly one value (among the complex numbers), and not two. So in a sense you're "starting" from two different points, which is where part of your confusion is.
The LHS (left hand side) of your first line has a unique, unambiguous interpretation among complex numbers. The two bits become (2i)(3i), which only simplifies to -6, and not to 6. If we had wanted to indicate the negative (opposite) of either of those bits, we would have instead written something like -√-4 instead, which is our convention to avoid ambiguity. It is possible that you were not aware of this convention, either, which would contribute to your confusion.
The radical sign, used together with other symbols, is used to denote unique complex numbers, according to a given convention. But the act of taking a square root (and not just pushing radical signs/symbols around) does introduce the possibility of two roots. But in a mathematical argument, one has to keep track of, and consider every step. Your conclusion is false because you're confusing the two usages. Your original LHS is only, exactly equal to -6, by our conventional notation. to get +6, simply put a negative sign in front of either radical, and bracket as necessary to avoid further confusion.
>>7999862
I'll make it simple. If A = B, then A^2 = B^2, but the reciprocal isn't true. With a simpler example you'll see:
x = -3
x^2 = 9
x = +/- 3
But only one value of x is correct.
> tl dr: Squaring an equation may induce incorrect solutions, you have to check them in the original.
> There is nothing fundamentally wrong working with sqrt(-4) in the pure algebraic sense (the number whose square is -4) and making algebraic manipulations with it. But remember it's not uniquely defined (assignation of i or -i is arbitrary) and you shouldn't drag this habit when operating with functions.
>>7997244
psych question
Various tests have labelled me as having sociopathic tendencies. No friends, apathetic, sardonic.. etc
however, in my neuroscience class I took a test recognizing microexpressions, and got a perfect score, twice.
Doesn't empathy and sociopathy contradict?
Does having low empathy cause someone to be more analytical?
To clarify, I'm using the word sociopathy seperate from psychopathy. Psycho being, emotional part of brain doesn’t light up. Socio being a dull or suppressed signal.
>>7999849
[math](\sqrt{-4}\sqrt{-9})^2 \ne 36[/math]
How do astronauts fap?
Can you get a boner in zero G?
Is IQ meaningful? And could someone link studies supporting their answer?
>>7999930
Your complex analysis teacher will congratulate you for your rigor and accurate understanding.
Your field theory teacher will fail you immediately after seeing you can't handle a simple algebraic operation in a field.
Why is computer science the best science?
>>7999976
Because it can simulate all other sciences.
>>7999876
Mathematics has developed very rapidly in about the past 200 years or so. So much so in fact, that texts become obsolete or irrelevant quite rapidly. This is why /sci/ discussion of reading material focuses on textbooks and not "original works". What true /sci/entists and mathematicians, etc, are interested in is less history, and more about whatever is relevant to their area, expositing it in a clear and up-to-date fashion. A math grad student is not (ordinarily) going to read Ars Magna, /either Principia/, or the Rhind Papyrus to get any worthwhile insight into modern mathematics, into his own area.
However having said that, if someone has an interest, then they will at certain times be interested in the history of what interests them. Historical interest is the main reason to read old math, and not deep mathematical insight of itself. I will assume that you share this interest with me, since I concentrated on both history and math in college.
cont.
>>8000025
The major exception to the above is Euclid's elements, yes, so I recommend that first of all. Look up some demonstrations online, be prepared to look up words elsewhere online, and decide if you want to continue and actually work on it. It is both a historically valuable text, and an ancient message of /properly/ mathematical (if simple) argument. People have been known to /complain/ about Euclid on this board; they understand neither history, nor math. I cannot overstate the next sentence. /We are still doing mathematics in the same way that Euclid did mathematics./ What do I mean by this? Obviously I'm not referring to the fields and tricks that we have now - we have a lot more of those now, the ahistorian will boast. Euclid is a meme, fuck Euclid, he might say. But I've pre-empted him about the latest, sexiest fields.
What did Euclid /do/? He thought carefully, experimented, thought some more, built on what others had done, drafted, edited, hazarded a few completely reasonable assumptions, and from those, derived diverse results, /using abstract chains of reasoning, which he then wrote down/. He /used/ certain results to build /even more, interesting results/. He then /organized/ what he had done. Even the way that the /page/ looks is fundamentally the same as what we prepare today: a page, mostly text, also punctuated with formulas and the periodic diagram. Regarding abstract thought on measurements, quantities, signifiers, and their relationships. The activity I'm describing sounds an awful lot like the routine in a profession that I can think of.
There is a reason why Euclid was actually used as a math textbook up until about a century ago. The vocabulary has changed and we've gotten into sexy algebraic geometry and IUT and so on, but Euclid's intellectual activity and creative work are fundamentally the same thing that we do today. That part hasn't changed. That part has stayed the same.
Euclid is not a meme. Euclid was the real deal.
>>8000030
>>7999876
Continuing with the above, the Elements is a solid "math classic". Let's talk about some other historic texts, along these lines.
First of all, just to make it clear, there are two texts called "Principia Mathematica". The first is the physics text by Newton, and the second is the early 20th century work by Whitehead and Russell, on foundations of mathematics. You absolutely do NOT need to read the latter, its notation is atrocious, and it was largely BTFO and criticized by Godel and Wittgenstein, respectively. It is one of those "obsolete" books that I mentioned earlier, studied now mostly as a historical curiosity (because it does get mentioned a lot due to the history around it), as I said. If you really really really like physics, you might read an annotated version of the Newton text, but again, this is not a way to learn physics for the first time-we have textbooks for that.
Many people seem to like Polya-How to Solve It, so I'll suggest that one, it's not long but I haven't read it. For aesthetics, there's "A Mathematician's Apology" by Hardy, where he defends pursuing pure math for its own sake, giving his own opinion on things. This attitude causes many on /sci/ to cringe, but the latter is also quite short, and then you've read "a historic document" about /why/ people do math. And you get his version of things so then you can decide for yourself how you feel about it.
Some technical articles (actual math/logic) which are fairly short and historically important are Godel's incompleteness proofs, and Riemann's "On the number of primes less than a given magnitude". You can get cheap copies of these through Dover if you know where to look.
Apart from these, it's whatever textbooks are good, and /sci/ has threads on that topic regularly.
What is the matter inside a black hole like? I know neutron stars merge protons and electrons into a dense lattice of neutrons. Increase the gravity and then the actual particles never seem to be talked about
I've been looking at textbook examples of showing that something is a subspace but they all seem to lack definitiveness.
For example with showing that the set is closed under addition, they merely do the addition and then state that the result is in the right form.
For example the set of matrices
[eqn]\begin{matrix} x & x+y \\ x-y & y\end{matrix}[/eqn]
under addition becomes
[eqn]\begin{matrix} x_1+x_2 & (x_1+x_2)+(y_1+y_2) \\ (x_1+x_2)-(y_1+y_2) & y_1+y_2\end{matrix}[/eqn]
Intuitively I can see how they are in the right form, but is that enough to show that the set is closed under addition? Just associating the variables?
>>8000265
You need to show that adding two elements of a set gives you an element of the same set, which is exactly what you've done. This is completely rigorous. It just so happens that membership in your set is determined by a matrix having entries of a certain form.
You know how the model of the atom has changed over the decades?
What are some thoughts or ideas for future modifications to the current model of the atom?
>>8000227
Thanks again, very helpful!
>>8000361
Beautiful. Thanks a lot anon.
>>7997244
I'm trying to create a recursive descent parser. So far I have all the foundation set, I just need to properly implement a few functions to enforce the grammar. I thought everything was right, it looks it, but I guess my Aop, Expr, or Term function is doing something wrong. Sometimes the input stream gets cut off and things aren't recognized. I don't see how though.
Is there any site or source that explains this more in depth, with code examples? Everything I've seen is very generic, which is fine, but I'm stuck on implementation.
I've searched the web near and far, and have not found any examples that helped me understand this; pls halp.
Here's the Expr Function [:::](http://pastebin.com/fzjcugme (embed))
This is the grammar : [Grammar](http://imgur.com/OrBnpEk)
Here's the main program with all functions. [Program](http://pastebin.com/qMB8h8vE (embed))
Please God, someone, anyone, help me. I want to see the light.
When am I ever gonna use polar equations outside of school?
>>8000245
Theyre trying to find stuff like pentaquarks at the LHC right now. One reason is that the inner parts of neutron stars and black holes may be super dense, exotic mesons. Its unlikely black holes will bemultiquark mesons, but understanding neutron stars always helps in furthering our understanding of their black hole cousins.
>>7997534
Check to see if your natural gas pipes are leaking.
>>8000497
whats your major?
So I've had the fundamental theorem of calculus explained to me several times, seen formal proofs, "intuitive" explanations, watched several videos, and I still don't feel like I'm completely get it. Is this one of those things that just suddenly sort of "clicks" after a while?
>>8000558
no. you won't use much math at all. its cool if you just brain dump everything.
>>8000574
With an emphasis on not being a codemonkey, so likely
>Abstract algebra
>Discrete maths
>Calc I-III
>Linear Algebra
>>8000569
i didn't really understand calculus until i took ODE's.
>>8000499
That's actually very helpful and now I have a better understanding of what to research. Thanks
>>7997931
This happens when for 'under damped' systems. Looks for complex roots in the characteristic equation. Open your book, or watch the MIT diffeq lectures. You might learn something.
life is vibration, energy and frequency..right? so if you mess with those things. why would you not think it would have an impact....? https://www.youtube.com/watch?v=82V6E4sm054&nohtml5=False
>>7998543
Do sequences like this have a particular name?
Didn't think people would like it if I tried to make a whole thread on it, and not sure how familiar /adv/ is with the subjects.
What would you guys say about my decision in double majoring in biology and mathematics? I don't want to do bionformatics or some meshed major, but as two separate ones. I love both topics a lot, and I feel by choosing one in missing out on either job opportunities or even the satisfaction of knowing both.
If it helps,!I'm trying to build a cabin and become /out/ hermit later in life, would build a home with my dad. If all goes to shit I would end up doing some comp sci stuff from home as my job to try and pay for the land. Either way I'd still be happy I knew my passions.
Criticism welcome, my question being does /sci/ think this is reasonable.
>>7997244
http://www.ustream.tv/recorded/85314345#to01:05:31
what is this?
>>8000691
What kind of mathematics would you want to major in? Have you been exposed to epsilon-delta proofs yet?
>and I feel by choosing one in missing out on either job opportunities
Have you done any research on the current prospects of biology undergraduates besides what the uni told you?
>>8000691
Multiple majors are always a bad idea unless you have some scholarship paying
>>8000569
Have you just seen formal proofs or written a formal proof for it?
>>8000718
Still in high school, 18 year old but still a generous amount of time before I commit to any schools or majors. Not familiar with what kind of specific math I want to get into, so thanks for the heads up.
>>8000726
I guess I wasn't familiar with this, is it that much more expensive to commit to a double major? I figured I was just going to have no room for electives and maybe some extra classes on top of it but not an extraordinary amount. Money is somewhat of an issue so I'll try and research that more
>>8000756
In my program you can double major by taking an extra semester, but that's only because some of the programs are so similar.
I think it was around $5000/semester?
Use the time you have in school to learn how to learn new things. Then just study the one you don't want the career in in your spare time.
Or switch degrees in grad school...it's often not too hard.
Talk to your advisor or dean if you don't have one yet. They'd know more about your situation/school
>>7999876
Most math classics are not a pleasant read and with good reason. There is a reason why people hold seminars to discuss and refine proofs and theorems are often proved several.
The first time something is introduced rarely has anything to do with the way it is taught later on and a lot of expository work is usually necessary in order to make the idea intelligible (I encourage you to read some of Galois' papers to see what I am talking about).
That being said, there are still some works that might be an interesting read: Euclid's elements and Gauss' Disquisitiones (his work does not suffer from the problem that I mentionned, because he spent a notoriously long time thinking about exposition), for example.
Also, math from about a century ago is fairly readable so the original works of Poincaré, Riemann and the like are probably within reach
>>8000756
Don't listen to the dumbfag, double majors aren't even challenging unless you're doing some engineering major with a booked up schedule, math and bio are both pure subjects that leave a lot of extra room in your schedule and both would definitely work as a double major.
That is, committing to 2 whole majors before you start college is kinda silly, most people end up changing even their one major, but don't rule it out, it's doable. It's a lot of work unless you pick subjects that complement each other like math/physics but not too much.
How do I git gud at math
I feel like a piece of shit for not being able to understand lessons very well and having to spend most of my study time on it
I'm 18 but I look 14. I have a deep voice, a relatively high amount of body hair (no facial hair) and a pretty well developed body except for the fact that I am a manlet. Wtf is wrong with me? Am I a late bloomer or is my puberty broken?
>>8001369
Become girl.
>>8000767
Thanks anon, will do. Extra semester isn't too bad but a counselor would know my situation best.
>>8000903
Oh I'm for sure not commuting yet it's just an idea I've been having, wanted to do something science related for a long time but have a hard time deciding on one subject. I realize they don't compliment each other greatly as bio is a lot less math heavy than Chem or physics but I think it would be interesting to try to use them together in some way, if not at least I'm happy knowing both.
>>8000888
Hence my earlier mention of Riemann's little paper on number theory. :^) nice double-trips btw
I've heard someone say PCA differs from FA in the sense that it isn't a "statistical linear model" or something. How come is FA linear model but PCA not? What is linearity here?
And what the heck is an eigenvalue in the context of FA?
![1920px-Schotten-Baumann[1].png](https://i.imgur.com/n6jk7Qv.png "1920px-Schotten-Baumann[1].png")
Why the fuck is this a named reaction?
i have a stupid question
>>7999343
Bump, don't ignore me you faggots, if it's so ez then explain it to me!
>>8002059
if a=b then 1/a=1/b
How much does job experience matter for getting a STEM job?
I was planning on interning next summer but my dad wants me to get a part time job this summer in a grocery store or something. Is he right?
What's the like, fundamental truth regarding the difference between a population and a sample? It just seems sort of arbitrary to me
>>8002049
Because it doesn't scale linearly
e = 1/2m*(v SQUARED)
How do you take notes /sci/?
I'm studying from walter lewin's lectures + a book, but I think my method of taking notes is too shitty. I tend to forget half the lecture, is there a note taking guide or something like that? Excuse me for being a brainlet, just self-studying because I don't want to be too retarded. (Also, taking notes from books?? I don't really get it, can anyone point me towards a study method?)
>>8002305
I'm struggling with the same fucking problem
If I'm studying calculus, do I ready need to know or understand the proof of something? Isn't it enough just to know that a formula or equation always works a certain way?
>>8002305
Really the repetition is what helps me. If a professor is explaining a problem, I not only write down the steps but include a summary of how that step was executed in the margin. If you're self teaching, you can also pause the lecture, go over the notes you have, and include any other observations you have in the margins before jumping back into the lecture. As far as books, just highlight the points and write those down in a separate notebook. I can give examples if you want.
>>8002344
Please do.
>>8002333
If you're not a math major OR you aren't a physics major OR you aren't an engineering major OR you aren't taking any higher level math (anything past Calculus I), then you will probably be okay not knowing a lot of the theory.
Otherwise, take the time to at least understand the idea / theory behind calculus at a basic level.
Should I keep going with CS ?
I just finished my first year of college and I'm not sure if I want to do programming for the rest of my life.
Can someone explain what blackbody radiation is from the big bang? So the light from the big bang is traveling towards us. Is this light from the edge of the universe? Will all the light from the big bang eventually reach us and there will not longer be any blackbody radiation?
>>8002379
CS doesn't necessarily mean you will have to get a job as a software developer.
Maybe check out CE or EE?
>>8002385
I wish I knew what other stuff was like. I don't really have any way to get an idea of it. I would have done mech e but I hate doing anything related to CAD. Had an engineering class in highschool and I sat in front of a laptop making things for an hour a day.
I should probably watch youtube videos or something.
What is being an EE like?
Engineering major here, in my applied quantum mech class we're discussing density matrix formalism, can anyone recommend a good reading resource to learn more about this? Also looking for recommendations for anything related to WKB approximation
>>8002390
No idea. Typically a good amount of overlap with computer engineering. A bare minimum of CS.
Here is the EE program at my university, it's probably very similar to EE programs across the country. Basically it's part physics (electricity and shit, obviously), part math, part CE (computer architecture, microprocessors, etc...), with a sprinkle of CS.
>>8002409
https://www.ship.edu/Academics/Programs/Undergraduate/Electrical_Engineering/
Forgot the link.
>>8002409
It would be easier if I could be interested in something. I don't know why but I've never been interested in anything so I just decided on CS randomly.
If I have a standard normal distributed random variable X with mean μ and variance σ2, what is a confidence interval again? Specifically, what is the 95% confidence interval?
>>8002409
At my uni there are big parts related to signal processing as well as RF and the like
Lots of matlab
>>8002379
Depends, you could go into theoretical computer science if your university offers this track. It is basically applied mathematics however. Look up some classical computer science problems and see if those do anything for you. If your uni is worth its salt itll offer some actual computer -science- classes besides programming as well after your first year. Have you looked into that?
If you decide to stick with computer science it does not neccessarily mean youll be stuck programming. You could go into an advising role (consultant), or if you play your cards right something quantitative or a managing function.
>>8002422
Eh, right now I'm going to a community college and getting a transfer degree, so they don't really offer any of that stuff.
I'm just worried about not knowing enough and not being able to get a job. Something where you get a degree or pass a test and get certified, and that proves you can do a job seems like it would be less scary.
>>8002414
It's never a good idea to randomly pick a major. If you're STEM minded, but not very good with math, and have no interest in programming, then maybe check out biology? I don't have any good advice for you, considering I know nothing about you.
I get the feeling that maybe you'd be better off in a business major or something similar. I knew a guy who was really smart, majored in Physics, got beat down, and went into Finance. He's doing pretty well now.
>>8002428
I don't even have any idea if I'm math minded or not.
I'm in precalc now and I have an A, although that doesn't really mean anything.
Never took anything hard in highschool because I didn't want to do more work.
>>8002424
That's a normal feeling for a freshman. Maybe you should stick with it, keep improving yourself, keep practicing, have a positive mindset, and you'd be amazed what you can do. Sounds cheesy, but it's true. People underestimate themselves all the time.
>>8002433
haha, if you got an A in precalc, then calc I is gonna be a joke.
anyways, I've given you enough to think about. Best of luck.
>>8002424
>I'm just worried about not knowing enough and not being able to get a job.
The longer you study, the more you become aware of all the things you do not know.
You should make a list for yourself of some alternative majors, a cs major, and all their pros and cons.
>>8002439
>The longer you study
I don't really study though. I just complete the homework and that's it.
>>8002462
You could always do some extracurricular ideas. Just throwing down some ideas.
>>8002380
We don't see as far back as the big bang only the epoch of recombination which is when the universe became transparent.
It's not quite the horizon, non-light based methods like neutrinos and gravitational waves could probe further but back then light couldn't travel far so none of it survives to this day. It is very near the edges of the observable universe.
At each moment CMB light reaches us so we see a slightly further away patch of the universe the next time we look which recombined at the same time but the light took longer to get here because it was further away. (in reality we don't see one exact part, recombination wasn't instantaneous). In non-accelerating cosmologies this could go on forever, seeing more and more distant light with the CMB moving to longer wavelengths. However with dark energy the horizon is limited so the CMB will in the very distant future disappear.
>>8002468
That's why I'm unsure in what I'm doing. Other people seem to care about CS and do extra-curricular stuff and read about thing etc.
I just get the homework done and then look at 4chan/play videogames sometimes.
>>8002469
I remember reading somewhere that the James Webb Space Telescope will help us probe even earlier into the universe. If this is true and you're aware of it, how is it possible if for JWST to see past recombination? What makes it different from Hubble?
Are there any people here who are working with a mathematics degree?
What kind of work can I expect to be doing with one?
I'm two years into a math major and I'm starting to get the feeling I should start career planning before it's graduation and I need a job ASAP.
>>8002472
this is why I changed out of CS. it seemed like you had to make your whole life CS. not working on coursework? go make some apps or build some websites or you'll NEVER get a job.
the companies in the industry have really shady practices too, they'll say that they need a ton of new engineers but at the same time are firing a lot of the older ones.
>>8002491
What did you change to?
Also I think my problem is more of a general can't care problem.
I wonder if I have brain problems sometimes.
I probably have autism or something.
>>8002496
I'm in electrical engineering now.
I have the same mental thing as you. I really do not give a shit about this stuff but I'm not bad at it so I don't really know what to do. I don't really care about anything.
It's 1am and I can't think for shit. Can anyone help me?
>>8002487
Finance basically
So banking, accounting, actuarial etc
Companies like giving internships to math majors, try to get one the summer before your senior year
>>8002597
...........
>>8002613
I know its just basic addition/division, but I'm a lazy fuck.
>>7997244
Question: What are some good Algebraic methods of simplifying polynomials of degree 2 or higher in order to find their roots?
>>8000672
arithmetical series ...i thought people learned that in high school ?
>>8002469
great answer. Thank you
>>8002059
if a=2 then 1/a=1/2 dumbfuck
>>7999920
recognizing microexpressions has nothing to do with empathy , you can memorize them by definition (scrunched eyebrows and pursed lips is anger ) where a psychopath is a highly manipulative person and will learn that and read them correctly exactly because you lack empathy ...empathy is more of a feeling in recognising emotions and social situations where you share an emotional connection with someone (making someone feel bad makes you feel bad, making someone feel good makes you feel good) so sociopaths don't pick up on those feelings (can make them seem rude or uninviting if you unintentionally hurt someones feelings because you just don't understand or don't care that what you are saying is hurtful )
there is no correlation in empathy and being analytical but it can make some hard decision making targeted twoards others (firing someone or dealing a death sentence etc. )
>>8002620
Check for easy roots : 0, +/-1, +/-2, +/-i
If the polynomial is biquadratic (ie of the form ax^4 + bx^2 + c), then make the change of variables u = x^2. You now only have to solve quadratic equations.
If the polynomial is palindromic (ie. the coefficients are symmetric with respect to the middle one) with even degree, then you can make the change of variables u = x+1/x. You have now reduced the degree by half and will only have to solve a bunch of quadratic equations in the end.
As a general rule of thumb, it is always easier to solve two equations of small degree rather than one equation of large degree.
If you are looking for rational roots with a monic integer polynomial: Study the function (ie. differentiate it, graph it and estimate the location of zeros). The zeros are then actually integers, therefore very easy to check if you have even crude bounds on the intervals where the function vanishes
>>8002484
It's not true i'm afraid but it would be nice. What JWST will do is see earlier than the Hubble deep fields to some of the earliest galaxies.
At recombination there were no galaxies or even stars. After recombination the gas just cooled and started collapsing. Only radio has a chance of looking into the dark ages. Then there was first light with the first generation of stars, that is the earliest a optical infrared telescope (like JWST or Hubble) will see (barring exotic things like primordial black holes).
Hubble is limited to galaxies at about redshift 10, simply because it's instruments don't go very far into the infrared. As you go to higher redshifts as I'm sure you know the observed light is at longer wavelengths, this is fine until the source isn't emitting at the shorter wavelengths. This lyman break is where the hydrogen gas strongly absorbs the UV cutting off the blue tail. The lyman break is used to find the highest redshift galaxies but it also means you cannot find these objects if you can't work in the infrared. The further you go the deeper you can go. JWST will get to at least redshift 15 perhaps 20 with help from big surveys from other telescopes to find extreme objects. Recombination happened about redshift 1100!
You may be confusing the epoch of recombination with the epoch or reionisation, the latter of which is a hot topic and one of the key goals for JWST and the coming generation of 30 meter class telescopes. After first light the gas in the universe was heated and at some point recombination was reversed. We don't know exactly when or how it happened but it was around redshift 7-12. The problem is it's quite hard to study. Hubble isn't sensitive enough to show us the faint galaxies back then so we don't know many there were and we have to extrapolate. JWST will change that.
....
How do I find the derivative of 2^x?
I can find plenty of stuff saying what to do, but it leaves me wondering how they arrived on that conclusion.
>>8002732
Alright. At first we take the change of the function and divide by dx:
(f(x+dx)-f(x))/dx=2[(x+dx)^2-x^2]/dx=2[x^2+dx^2+2x*dx-x^2]/dx=2[dx^2/dx+2xdx/dx]=2[dx+2x]
Then we let dx->0 and we get df/dx=2[2x]=4x
QED
>>8002731
The big advance with JWST is not just sensitivity and wavelength but also information. Hubble gives us almost nothing on these high redshift galaxies. At best a crude redshift and some information about the age of the stars. JWST gives us not just imaging but spectroscopy, it has a very good spectrograph which will measure the brighter high redshift galaxies in detail. Hubble on the other hand despite having a magnificent UV spectrograph (which I am working with) can't really do sensitive infrared spectroscopy.
JWST won't be sensitive enough to see the first stars but there is a slim chance it could see the death of one. These would be the spectacular supernovae of hundred solar mass stars.
It's going to be quite transformative. It probably won't rewrite cosmology but it could rewrite galaxy formation. The pictures should also be superb.
>>8002732
Shit, I misread.
You know that the derivative of exp(k*x)=k*exp(k*x) right?
So we have:
2^x=exp(ln(2)*x)
so differentiating it we get: df/dx=ln(2)*exp(ln(2)*x)
remembering that exp(ln(2)*x)=2^x we substitute that in getting:
df/dx=ln(2)*2^x
>>8002751
How badly did you fuck up to misread "2^x" then give an insanely complicated answer?
But anyway, what I don't get is how you got to exp(ln(2)*x). x=e*lnx makes sense at least.
>>8002099
relevant experience > experience > attitude > how well you did in uni > what you did in uni, assuming identical qualifications
Do unpaid internships.
What are applications like the Mean Value Theorem and Newtons Method actually used for?
>>8002620
For all univariate (one-variable) polynomial equations, you can transform it into an equivalent /monic depressed univariate polynomial equation/, or what I refer to as an "MDUPE". A monic polynomial is simply (trivially) a polynomial whose leading coefficient is one, while a depressed polynomial is simply one whose next-highest term vanishses/has a coefficient of zero. depressed polynomials were used to solve cubics and quartics back in the day.
What I am describing is a special case of what is sometimes called a "Tschirnhaus transoformation", but it turns out to work for all polynomials, regargless of degree. In the case of low-degree polynomials, it can constitute the first few steps in a general algorithm to find those roots, and it may apply in special cases for higher degree polynomials. There's three steps: a trivial one, an interesting one, and a tedious one.
1) (trivial): divide through by the leading coefficient.
2) (interesting): make a substitution of variable of the form [math] \displaystyle x = t - \frac{b}{na} [/math] , where x is the variable of the original polynomial, t the substitute variable, a the original polynomial's leading coefficient, b its next-highest coefficient, and n its degree.
3) (tedious): rearrange in terms of your new variable t.
Works for all polynomials but I have to review details. pic related is part of an article I'm writing myself on the topic, ideas I've hashed out in previous /sci/ threads.
one set theory problem has me hung up
let A be a set with n+1 elements, where n is in the set of whole numbers. Let s be in A. Show that A \ {s} has n elements.
(equinumerosity)
It's the last problem so I'm about to say fuck it
>>8002820
The mean value theorem is used often in proving that someone was speeding. If you ever see "speed enforced by aircraft", the way they do this is record the time it takes your car to travel between two known points and from there compute your average speed. Per the mean value theorem, there was a point on that interval where your instantaneous speed was equal to your average speed and therefore you were speeding. There used to be devices actually in police vehicles that would do this - they measure the distance between two easily identifiable points, input this to some device and then press a button when you hit the first point and again when you hit the second and it does the calculation. This system has largely been dropped (at least in the US) in favor of radar systems that give actual instantaneous speed.
Newton's method is used in optimization to find the zeros of a function (specifically the derivative), but I'm not too familiar with optimization problems
My teacher said that this problem could be solved by energy or by angular momentum.
Is he ling or am I shit?
>>8002867
you're shit.
>>8002870
Fugg.
I suspected so.
Thanks anyway.
>>8002755
Ok, let's do this:
ln(2) is the natural logarithm of 2.
2=exp(ln(2)) right?
now, (e^k)^x=e^(k*x)
now 2^x=(e^ln(2))^x=e^(ln(2)*x)
now, for f=e^(k*x), df/dx=k*[e^(k*x)]
if we then infer that since 2^x=e^(ln(2)*x), we can substitute k for ln(2), we get that 2^x differentiated is ln(2)*(2^x)
>>8002913
Isn't angular momentum L = Iw?
The paper states that I = (1/2)MR^2.
Why haven't you squared the radius?
>>8002951
I fucked up because I'm retarded.
>>8002951
Sorry, guy deleted his post and I responded to you by accident./
Sorry for what's probably a shitty way to type this:
If D^[n-1]x^n= (n(n-1)...2)x, then why does D^[n+1]x^n=0? Apparently D^[n+1]x^n is the derivative of a constant but D^[n-1]x^n is not, and I can't wrap my head around why that is.
>>8002953
I suspect that my momentum method is correct, but my teacher told me that the problem can be solved by energy methods. I have no idea where I'd start with that.
He frequently makes petty mistakes and and is often sleep-deprived so I really don't know which of us is wrong. He could mean "you can solve it through energy methods which you don't have the tools for yet."
>>8002951
This is analogous to complete inelastic collisions where conservation of momentum states that m1vi=(m1+m2)vf, vf=vi*m1/(m1+m2)
while conservation of energy states:
½m1vi^2=½vf^2(m1+m2), so vf=vi*sqrt{m1/(m1+m2)}
Change speed to angular frequency and mass to moment of inertia.
Now, the answer to this is that energy is lost to heat and shit. You cannot get the same result from them.
Conservation of angular momentum dictates the end angular speed.
Good luck son.
>>8002958
D(x^n)=n*x^(n-1)
for a being a whole, positive integer smaller than n:
D^a(x^n)=n!/(n-a)!*x^(n-a)
for a=n-1 we get
D^(n-1)(x^n)=n!*x which is a line.
D^n(x^n)=n! which is constant.
>>8002975
Completely forgot about elasticity stuff.
I usually do the homework and problem sets, and review the all the class in the week preceding the test. The next test is in a little while, and it's been a month since elasticity, which hasn't come up again. I should try reviewing small portions of such at more frequent intervals. Thanks (and thanks to >>8002870) for the heads up.
>>7997244
If you know the four basic radians of the unit circle: pi/6, pi/4, pi/3, pi/2.... etc.
Is there a way to find their corresponding values in the other quadrants? Other than figuring out what the angle is and then converting it radians.
For example, if I have pi/6, and I want to find its corresponding value in the fourth quadrant, 11pi/6, how can I do that?
Preferably, something where I can add units of pi to the radian I already have.
>>8002823
Damn son. I'll try this. Right now I'm in Differential Equations jutsu, and in order to solve for the general equation you have to factor it out properly.
Its a pain in the ass once the degree is four or higher.
>>8003009
Just use your head man. Draw a sketch of the axis, label where you are and what quadrant you want to be in and then just use basic (and I mean BASIC) arithmetic. Practise it a bit and you'll be good at it within a week. Never underestimate the importance of sketches, especially when it comes to radians, vectors and complex numbers.
I am trying to assist in teaching a "grocery math" class, and I am trying to establish a formula to solve a word problem I've been given. I have spreadsheets and shit that do it for me when I'm working, but I want to understand. Please help.
"If you sell $1000 of a 25% margin item, and your target margin is 50%, how much do you need to sell of a 75% margin item to end at target? How about 2 items at 60% margin?"
so in the deep end of mathematics, i've noticed circles talking about algebra vs geometry
what exactly characterizes algebra and geometry?
i know there's some REALLY deep stuff involved, and i've just completed complex analysis, but i don't want a hand-holdey answer
>>8003024
[math]\frac{250+.75*x}{1000+x) = .5[/math]
>>8003215
Well it worked in the preview, I must've made a typo
[math]\frac{250+.75x}{1000+x} = .5[/math]
>>8003223
How about 2 items at 60%?
>>8003254
I don't quite understand what you mean by that, sorry
>want to look up linear constant coefficient difference equations
>Google considers difference to be the same as differential
Is IQ meaningful? And could someone link studies supporting their answer?
>>8003258
It's cool, I was able to figure it out.
{Sales(AMargin%) + x(Bmargin%)]/(sales + x)=Zmargin %
>>8003280
No. I tested at the 97th percentile, and I'm dumb as a box of chocolates. Actually, just yesterday, I hurt myself getting out of bed. Went to grab the covers to throw them off of me, jammed my thumb directly into my nipple. Hurt for like half an hour. Not even kidding.
>>8003290
No offense, but anecdotes don't constitute science.
>>8003260
try quotation marks
>>8003292
See?
C++ help
basically my c++ homework is asking to construct a simple atm where the code with calculate the new balance after a withdraw or deposit has been made. Can someone assist me with creating a function for my cases?
>>8003297
Dzięki
>>8003319
cout<<"enter withdraw:";
cin>>with;
if(with>balance)
cerr<<"you fucked up nigger\a\a\a\n";
else
balance-=with;
>>8003341
thank you for the code and another stupid follow up question, do i insert all of this within case 2?
Why is the electric field from an infinite plane constant?
>>8003319
I'll write it for you
Int main(){
run = true;
int balance = 0; //don't what intital is
while(run) {
string action = "none";
int amt = 0;
cin >> action;
If(action == "quit") {run = false; break;}
else if (action == "deposit")
cin >> amt;
balance += amt;
else if (action == "withdrawl")
cin >> amt;
balance -= amt;
else
cout << "Invalid Action! Valid actions are 'deposit', 'withdrawal', and 'quit' \n"
}
}
>An electric motor turns a flywheel through a drive belt that joins a pulley on the motor and a pulley that is rigidly attached to the flywheel as shown in the figure below. The flywheel is a solid disk with a mass of 55.5 kg and a radius R = 0.625 m. It turns on a frictionless axle. Its pulley has much smaller mass and a radius of 0.230 m. The tension Tu in the upper (taut) segment of the belt is 175 N, and the flywheel has a clockwise angular acceleration of 1.67 rad/s2. Find the tension in the lower (slack) segment of the belt.
I got the answer by assuming the flywheel has a moment of inertia of (1/2)MR^2 but some things online say I should be able to find the angular momentum of the pulley and start from there.
The hell do I do that?
How would you find the value of something like [math]\sum _{n=1}^{\infty } \frac{1}{(4 n+1) 3^{2 n}}[/math]?
I think I probably have to substitute [math]x=\frac{1}{\sqrt{3}}[/math] to get [math]\frac{\sum _{n=1}^{\infty } \frac{x^{4 n+1}}{4 n+1}}{x}[/math] and then derive it, but how can I just say [math]\frac{1}{1-x^4}=\sum _{n=0}^{\infty } x^{4 n}[/math], and integrate to get [math]c+\frac{4 x^3}{\left(1-x^4\right)^2}=\sum _{n=0}^{\infty } \frac{x^{4 n+1}}{4 n+1}[/math] then divide by x? I don't think I can just get rid of the c, can I? I mean, if I substitute 0 I get that c=0, but does that let me just leave it off?
Ok so if we have a group of 10 elements, prove that the number of elements x in G such that x^5 = 1 is divisible by 5.
I had this on a test and I don't think my answer was right.
>>8003409
What does the first half of your first line have to do with the second half?
In the current year, would it be possible to use miniature atomic explosions as a propulsion method for high-speed, long-distance travel?
The spacecraft can still leave the atmosphere using conventional propulsion methods (rocket+detachment stage), so radiations can't cause damage, then last stage would use the miniature explosions only.
As alternative the spacecraft could also be launched from a station already outside of the atmosphere.
Thoughts?
>>8003409
have you already learned the sylow theorems?
by sylow's 1st theorem there exists an element of your group of order 5, take a generator y.
then 1, y, y^2, ..., y^4 are all in the subgroup of things satisfying x^5=1
by lagrange's theorem the subgroup of things which satisfy x^5=1 divides 10, and its at least 5 so it's either 5 or 10 which are both divisible by 5
>>8003401
Use [math]\frac{x^{n+1}}{n+1} = \int_0^x t^n dt [/math].
You get
[eqn]
\sum_{n=1}^\infty \frac{1}{(4n+1) 3^{2n}}
= \sqrt{3} \int_0^{ \frac{1}{\sqrt{3}} } \sum_{n=1}^\infty t^{4n} dt
= \sqrt{3} \int_0^{ \frac{1}{\sqrt{3}} } \frac{t^4}{1-t^4} dt
[/eqn]
Which is straightforward to evaluate.
Yo can someone verify that I'm doing correctly? I haven't been to class because I've been busy and we have a test on this stuff tomorrow.
If someone can look at what I did and tell me if it's right or wrong that would be great. Just need help with this problem.
pic related
>>8003610
Can you post a good pic, can't read that
>>8003610
looks good but usually the fundamental set is the set of all {c_1 e^{-x}+c_2e^x+c_3e^{-2x}} where c_1,c_2,c_3 are any numbers, not the thing you wrote below it unless that's some notation you use in class
have you tried actually plugging that y into the differential equation and seeing if it works?
If I were listening to music inside a soundproofed vehicle, then accelerated last the speed of sound... What would it sound like?
Would there be some crazy doppler effect or silence or what?
>>8003633
The vibrations would accelerate relative to you and cause ear damage due to a lack of dampening due to soundproofing.
>>8003628
I just recreated it in onenote, the camera on the surface is shit. pic related
>>8003629
Yh, that's the notation our professor uses it. Just the first time I see the Dy in the equation, wasn't sure if I had to the it the same way I had the other problems or use a different method.
I actually haven't, how do I do that?
>>8003651
I just mean that your y=... is supposed to be a solution for the differential equation you started with. And so you can plug it into D^3y-2D^2y-Dy+2y and hopefully get 0.
>>8003642
Oh... Makes sense.
If it wasn't soundproofed?
Less ear damage but still a cacophony?
>>8003506
Straight forward? Doesn't that involve tanh? Or is wolframalpha being a bully?
Having trouble with this truth table, particularly the first step - ~D● (B v A) →~C how do i work this out? Do i need to split this in to two parts?
Thanks in advance /scii.
~D● (B v A) →~C
~B v C
D→ (C●B)
--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐--‐
C → D
I already asked /adv/, no luck.
If anyone knows about graduate admissions, and can help me out I'd really appreciate it.
I did relatively well my first two years of college. I had a ~3.5 GPA, was involved in research, and a couple small-time programs. In the second semester of my junior year I was diagnosed with Cushing's disease. It's a brain tumor of the pituitary gland. I've had surgery two different times to remove it (March 2014, and August 2015). I'm going to be graduating this May with a degree in Mathematics, and approximately a ~3.1 GPA.
Until my tumor happened I had always thought I'd go on to get my PhD in mathematics, but I feel like the actual me wouldn't show through on an application.
My question is this: is there any way to communicate this situation on an application to graduate school? My professor from research my first two years will 100% vouch for me, but I transferred closer to home after I was diagnosed, and honestly only have 1 or 2 people that would write a recommendation for me here.
Thanks for any help.
>>8003789
Never mind, I realized you can get it apart into nicer fractions.
>>8003721
Nah just fucking with you anon i made that up completely
Could anyone explain this to me, x=time needed to fill up a pool through first pipe and y=time for the second. If pipe x needs 8 hours longer to fill up the pool than the pipe y, why the fuck is it written as x=8+y then?? I just can't wrap my head around this, even though it's trivial as fuck. If y does the job of x in 8 hours less, or x does the same job as y, only that it takes 8 hours longer, why isn't it then y=x+8? Please please please, just tell me what I'm missing here...
>>8004488
What? If y is the amount of time it takes pipe 2 to fill up a tank, and we know that pipe 1 takes 8 hours longer than pipe 2 to fill up the pool, the time it takes x would be y (time from pipe 2) + 8 (the extra time that pipe 1 takes). Not really sure how that could confuse you.
So I decided to shun away from physics first because I figured that aerospace engineering is more in line with what I wanna do. (Build Rockets)
Then I jumped ship to mech E this year because my understanding is that they are similar degrees and I can do more with mechanical.
Now, I haven't done a whole lot with mechanical engineering other than statics, but I'm currently enrolled in a physics III course for engineers. (Basically, tackling a lot of quantum physics, but doesn't get into relativity.)
So here's the thing - I am remembering why I wanted to do physics so much in the first place. it's absolutely fucking fascinating to me. I thought this course would be my most difficult, but I just fucking love it so much that the work really doesn't bother me. I also hear about all these cool physics projects and awesome mathematical concepts people in the physics department talk about, while engineering always seems kinda dull.
So I was curious /sci/, say I really wanted to go into physics/astrophysics, but I still want to be employed on some level. Is physics really a bad choice? Would dual majoring allow me some larger benefits? Perhaps another major entirely?
Any advice on this? I kinda just sperged out a bit, but I'm wondering if anybody ever faced similar decisions.
>>8004488
Pipe x needs 8 hours MORE than y. So x = y+8. If pipe y needs 3 hours then pipe x needs 11; 8 MORE than 3.
solve this pls?
>>8004702
or just show me which integral I need to compute?
>>8004699
>>8004488
Ok, I was thinking backwards. Basically, if X is a bigger value, and we equal that to the smaller value, in order for the bigger value X to be equal to the smaller value Y, we either have to fill the smaller value Y to match the bigger value X, or we can take away from the bigger value X, to match the smaller value Y. Thanks for helping clear the path to the enlightenment.
>don't mind me, just my OCD rigged brain forcing me to write all the "proofs" out so I can remember it easily, once again, appreciate it, thanks
>>8004879
>>8004699
>>8004488
>>8004540
Sorry, I forgot to quote you, I was concentrating too hard on not fucking up Xs and Ys.
>this turned out to look way more autistic than I could've ever wished for, just end my life
Is the electrical field inside a spherical cavity located inside a sphere of volume charge density [math] \rho [/math] zero, even if the cavity isn't concentric? Drawing a gaussian surface inside the cavity and calculating the flux through it, we should get [math] \vec{E} = 0 [/math], right?
>>8004891
I worded this poorly, I meant that the field is zero, not that [math] \rho [/math] is zero.
>>8004706
With a quick drawing, I'd say the figure you're looking for is (x^2 + y^2 - 1) + z^2 < 1, so that's the thing you have to integrate.
>>8004891
If you have a sphere of conductive material and there you have a cavity without charge, then the electrical field inside the cavity is zero.
Proof:
Calculate the line integral of E on a closed path that pass though the cavity (pic related). Inside the conductive material, E is always zero, so if E isn't zero inside the cavity, the line integral on this closed path would not be zero and the curl of E would be non zero, thus E = 0.
>>8004913
What if the sphere isn't a conductor?
Where can i find information on what fluoresces at 365nm uv. I realize there is no reason to order information like that but I'm just wondering what sort of cool shit you could do with a 365nm uv led.
So far i know you can set dental cement and detect counterfeit money.
>>8004914
idk, I guess that E != 0 in this case.
>>8004917
Look up UV photography, it might give you some ideas
I recommend trying it out on plants in your garden, especially flowers
Don't forget your uv-proof goggles though, unless you want cataracts!
>>8004934
Shouldn't the contribution to the cavity be zero? Since the line goes in and then out of it?
>>7998862
So cool! This is what we are talking about in my heat transfer clas right now!
>>8004958
wow so cool! what are u 12? kill yourself u faggot
>>8005114
i love you :D
