>no sqt in sight
What the fuck does pic related mean?
>>8070808
fuck you next time add "stupid" in the subject faggot
Hey /sci/, I'm looking for books or links about polynomial factorization that has many exercises (ranging from beginner level to advanced/challenge level), can you recommend me some?
>>8071337
Are you talking specifically about polynomials in one variable?
>>8071457
Yes! I'm sorry for being stupid and forget to specify.
>>8071475
One and two variables, actually.
I'm programming in C++ but haven't seen any real C++ programs yet.
Assume that I create a table
a|b|c|d
d|p|g|h
the width is 4 and the length 2 obviosly
but I heard that you count beginning from zero
does this mean I should program
int width = 3;
int length = 1;
if I want to follow a convention?
whats the glass-transition temperature of human flesh/skin
Hi could someone help me with pic related.
If the Euler-Lagrange equation is satisfied then why is the derivative of this Hamiltonian function equal to zero?
>>8073662
Differentiate the hamiltonian with respecr to x and it immediately follows from the definition
What mathematics subjects should I look into (Khan Academy or something) if I'm interested in Computer Science to further High School knowledge?
>>8072051
Create a two dimensional array like this;
int A[3][1];
You can assign values to each "box" of your table with a double nested "for" loop that starts from i=0 and j=0 and ends at 3 and 1 respectively.
>>8073712
Linear algebra. Search up "khan academy in a stick", it contains a shitton more material that comes with a worse GUI than the site itself plus a lot of older videos. Unless I haven't found those videos in the real site yet.
>>8073779
*A[4][2];
How do we fourier transform this? I'm thinking either represent sine as exponents or use fourier sine transforms? Leaning on the former
Can someone explain why/how is run differential stat better predictor of future performance then win percentage?
And how could more than one of
x > y, x = y, x < z
be right at the same time?
Anyone know how to get a p value from whats given here?
>>8074035
use the definition...that is, integrate over [0, 2pi] instead of (-oo, oo)
>>8074565
an order is meant to be a generalization of the 'less than/greater than' signs you're used to for real numbers. It's saying that part of being an order means only one of those statements can be true, just like for the normal less than sign only one of those statements can be true.
Given some relation on a set, it's not obvious that only one of those should hold.
>>8074565
You're defining sensible requirements to any reasonable usage of those symbols.
How do I stop studying and create? I've been reading books for a decade and a half and never built anything that wasn't an exercise.
>>8074565
But that is impossible, that is property one of the definition.
What are you even asking?
I mean, you could create a relation defined on set S so that two or the three can be a true at the same time but then that would not be an order, it would just be a normal shitty relation that isn't even worth studying.
http://sketchtoy.com/67016183
How would you prove that DE=DC=CE ? D is placed randomly on the circle, between B and C
This is the graph of [math]y = x^{y}[/math] which does some extremely weird funky shit that I have no idea what it's doing.
It doesn't even look like a function since it loops back around over multiple x values, so I'm not even sure this is legal or how to properly evaluate it. I know that WolframAlpha said that finding a solution for it maxed out the computation time allotted to me.
My question is just how can I find the 'maximum' value furtherest to the right of the curve? It looks like it's around 1.44 something and I'm wondering if that's significant or not? I originally thought it might be root 2, but it's not.
>>8075006
I don't have a deep enough knowledge of complex analysis to explain in detail why it happens, but it seems to me that this is what's happening:
Wolfram alpha solves for y using something called the Lambert W-function; you end up with W(-logx) in the form. The W function is only defined on the reals for numbers >= -1/e. So the largest viable x is x=e^(1/e), which is about 1.44.
>>8075032
Thank you very much!
Help me /sci/, for the life of me I can't figure this out and I feel like a moron. DIY job but math related.
I want to build an aquarium out of plate glass. The dimensions I'm looking at are
750 x 300 x 600
The source of plate glass I have is a single plate glass shower door of suitable quality. The door's dimensions are 1785 x 745.
There is also another piece of the same material with the dimensions of 710 x 780.
Assuming I make accurate cuts and don't waste material, will that quantity of plate glass suffice for the project?
Refer to the attached picture.
>>8075006
Just find the max of y = x^(1/x), which is the inverse function.
>>8075396
never worked with glass, but I'm guessing it's not as easy as cutting through paper. So my question is: once you start cutting, do you have to go through the whole length of the glass?
Or is it possible to cut a piece in the middle of the glass plate while the rest remains intact?
>>8075426
as long as you keep it on a level surface you can cut it without it falling apart.
>>8075426
>>8075431
My question was not about how to cut the glass. I'll use a fucking glass cutter. My question was whether the source material I have will suffice for the aquarium design. The total area of source material is more than enough, but it must be able to provide whole pieces of (in mm):
1x (750 x 30)
2x (750 x 60)
2x (30 x 60)
>>8075396
you can't.
can't your aquarium become 745*300*600?
>>8075439
I asked the question about how you cut glass because you can't use as much glass if you have to cut all the way through, as opposed to just cutting what you need without waste.
>>8075006
As someone else said just take the inverse function and find it's derivative. At x=e the value of y is ~1.445.
>>8075445
okay.
so how does one work that out? is it the solution for surface area?
god, since turning my mind and energy to editing and writing I've become as numerically sharp as a bowling ball.
I was half heartedly sketching out the net on a poorly scaled door for about 20 minutes before I realissseeejejehhjdksmdmdddddddkdd
>>8075528
well basically the easiest part is realizing you will need both pieces of glass (the surface of the big glass part is not enough)
then start with the smallest glass and see what you can fit in.
either 750*600 once OR 750*300 twice, which is almost the same thing. You're not getting any more from that piece.
So let's say we get rid of one 750*600 using the small glass plate, because it's easier to fit two 750*300 if you have to separate them somehow.
So now you're left with your big plate of 1785 x 745, and you have to cut:
one 750*600
two 750*300
two 600*300
the problem is with the 745: you can only fit 2*300 or one time 600 in that.
So if you start putting your 750*600, you will be left with a huge unuseable space of 750*145.
And the rest of the space is not enough to fit the two 750*300 and the two 600*300
What happens between these expressions?
How do I generally operate on the numerators and denumerators to get a common denominator?
>>8075735
Multiply the top of the first expression by the bottom of the second expression, and the bottom of the first expression by the top of the second expression.
What's happening is exactly this, then simplifying.
Fact: until just now, I thought SQT was like SQL.
What separates a formal system from a deduction system in that formal system?
Why is decidability an important property in systems like first-order logic which is semidecidable but in every case where it is not decidable the reason it is not is because the process is infinite. Is this something that is only important for computers?
>>8075745
Why would /sci/ make daily 300 posts threads about fucking database queries?
>>8075735
Multiply each term by the common denominator over the common denominator excluding the portion of the denominator that it already has. You're in effect multiplying the terms by one, but giving them a common denominator.
(x+2)/(x+4) is multiplied by (2x-1)/(2x-1).
(2x-1) * (x+2) = 2x^2+3x-2
(x+4) * -(x+3) = -x^2-x+12
(2x^2+3x-2)+(-x^2-x+12) = x^2+2x+10
>>8075766
So after multiplying the numerator of the first fraction by the denominator of the second fraction and multiplying the numerator of the second fraction by the denominator of the first fraction and then summing these products up to attain x^2+2x+12, why do we divide this by the product of the fractions' denominators?
This is something extremely simple but is somehow 0% intuitive. Should it be intuitive?
>>8075784
>x^2+2x+12
Meant x^2+2x+10
>>8075784
Think of it without the variables. If I wanted to add 1/2 + 3/5 I'd have to have a common denominator. Easiest way to do that is to multiple 1/2 by 5/5 and 3/5 by 2/2.
Then I just perform addition as I normally would.
bumperino
I have a congrulence of
86^65 mod 133
how do I simplify (get it in x^1 mod 133 form) that?
anyone know a good youtube video for explain the sequential criterion for continuity and limits?
>>8076347
brutish force
86^65 mod 133
86*((86^4)^4)^4 mod 133
86*(44^4)^4 mod 133
86*23^4 mod 133
109
am i stupid if i can't solve this
Should the Kroneckor delta (in the context of GR tensors) be written with its upper/lower indices disjoint from each other, like all other tensors with contra/covariant parts? i.e.
[eqn] \delta_{\mu}^{\ \ \nu} [/eqn]instead of how every author I've seen does it,
[eqn] \delta_{\mu}^{\nu} \, . [/eqn]
(Or perhaps it should be [math] \delta_{\ \ \mu}^{\nu} [/math] -- I've literally no idea since I've not seen it written like a "proper" tensor before.) I figure it doesn't really matter, because of the nature of the Kronecker, but I'd like to know what the proper mathematical notation is, for my autism. (All I have is access to physics books about this.) What about higher rank Kronecker deltas?
>>8077312
[math] \delta_{x, y} [/math]
>>8077312
If the author isn't going to use a popular method to represent it then he should specify what the unpopular method means. All that matters is that the reader understands that that symbol in that context is the Kroneckor delta. That doesn't mean that certain representations aren't more intuitive or elegant or whatever though. I dunno what the popular representations are in physics though.
>>8077312
The placement of the indices don't matter on the kronecker delta except for summation purposes. In terms of GR just think of it as the euclidean metric / identity matrix.
>>8077312
The Kronecker delta is symmetric in its indices, the order doesn't matter and thats why it is usually written as:
[math] \delta ^{\mu} _{\nu} [/math]
>>8077406
Do you know how to decompose a tensor with respect to the bases for the tangent and cotangent spaces using the tensor product?
If you write out this decomposition it'll make a lot of sense.
I haven't studied math at any high degree, but I think it would be interesting to be able to understand (or to at least read) any mathematical formula. Is there a good website/video that generally covers what all symbols/rules for them are?
>>8077533
The problem is, every field of mathematics uses and reuses tons of different symbols.
Theres not really a set definition for each symbol because the context matters.
You could try https://en.wikipedia.org/wiki/List_of_mathematical_symbols for a big list of mathematical symbols and their uses.
In the end, if you're reading some algebraic geometry paper, in order to understand anything, you're most likely going to need to know algebraic geometry or have someone translate for you.
>>8077565
and even if you have a translator converting the expressions to english, you're not going to know what anything means.
>>8070803
https://en.wikipedia.org/wiki/Lattice_(order)
Why are lattices defined via sup and not max?
For finite sets isn't max=sup?
>>8077606
sup(a,b) doesn't need to be either of a or b. a lattice doesn't need to be totally ordered
why do i get really annoyed when i see ppl posting plebtier shit on this board
>has no degree
>wants to browbeat ppl on their math knowledge
I want to ace 1st year ECE at UofT
What do?
Programming is not a problem since I've been doing that for 8 yrs. Studying some Integral Calculus rn as that's not included in the HS curriculum in Canada
I was supposed to prove the first line
Did I do something wrong?
>>8077719
Ah shit, nvm I found it
Could someone explain case 4? Why the negative was added for -(a+b)
>>8077914
a<0, b<0 => a+b<0
therefore |a+b|=-(a+b)
literally the definition of the modulus
>>8077914
better proof:
|.| is a norm so the triangular inequality holds.
>>8077933
It's a bit of common sense and already understood crap
But this book is introducing it in a way I'm not used to, proofs and all, and it's really fucking with my brain
How to get from this:
[math]
\frac{(-1)^{k+1}}{3} +
\frac{2(-1)^k}{3} +
\frac{2^{k+1}}{3}
[/math]
To this:
[math]
\frac{(-1)^{k+2}}{3} +
\frac{2^{k+1}}{3}
[/math]
>>8078089
-1 to the power of anything is either 1 or -1 so long as the denominator of what you're raising to is odd. This means that either k or (k+1) will have an even numerator. If (-1)^(k+1) = -1 then 2(-1)^k = 2, likewise if (-1)^(k+1) = 1 then 2(-1)^k = -2. Really raising (-1)^(k+2) is redundant because (-1)^k works the same.
>>8078089
Take (-1)^2 out of first two fractions, do the math inside brackets and multiply.
>>8078156
could you elaborate?
i don't understand where this (-1)^2 is
>>8078168
Sorry, not (-1)^2, but (-1)^k
>>8070803
How do i proof that if lim(a(n)) = a, then lim(nth-root(a(n))) = nth-root(a) ?
lim(a(n)) = a => lim(nth-root(a(n))) = nth-root(a)
>>8078171
still have no idea, can you draw up steps?
>>8078196
drink some 90 proof
>>8078196
[eqn] \lim_n a_n = a \Rightarrow \lim_n \sqrt[n]{a_n} = \sqrt[n]{a} [/eqn]
>>8078196
The root function is continuous.
>>8075758
Anyone?
I just finished a semester of college precal and am taking calculus next semester.
So I decided to download Spivak's calculus (third edition) and am seriously at a loss for some of these questions
How the hell do I even do pic related?
Am I screwed?
>>8079504
if you're struggling with basic quadratics in the first chapter you need to put Spivak down and go get a high-school algebra text
You're just wasting your own time trying to learn from Spivak at this point.
>>8079504
a) Come on, man
b) Do as the hint says
c) Factor y^2 in the expression and use b)
d) Factor y^2, see what you can do with that
e) Complete the square
>>8079512
I'm merely confused about exactly what it's asking
Perhaps if you could work a quickly I'd understand
I've dealt plenty with quadratic equations and other math, I just never took the time to actually understand the proofs and whatever so it's like rebuilding a foundation for an already built tower
>>8079524
You just need to do some algebraic manipulations of the equation.
>>8079524
What it's asking is extremely basic 10th grade algebra. If that confuses you you're way too inexperienced to be doing calculus at all, let alone rigorous calculus.
>>8079524
Read (or skim) Gelfand's algebra.
I don't understand Quantum Mechanics
None of this shit make sense
>>8077941
Spivak is actually proving that. You can't just claim something is a norm without showing it, especially in an intro calc book, and think that counts for anything.
I don't really know what my question is, but I don't see how a meteorite half a mile long can wipe out all major life on earth. I mean if you zoomed out on earth, half a mile isn't even a pixel, and this shit is going to kill everything? Not saying it's wrong but I just can't fathom that reaction.
Just installed MiKTeX and using the TeXworks editor. Am I meant to type up the info in a word processor and then just copy an paste it into TeXworks in the appropriate template or should I be doing it purely in the editor?
20% for rain on Saturday, and 30% on Sunday. What's the probability for rain in weekend?
>>8080260
texworks is bad.
use techniccenter or litterally anything else.
> Am I meant to type up the info in a word processor and then just copy an paste it into TeXworks in the appropriate template or should I be doing it purely in the editor?
No. Find a template, run the compiler on it and see what it outputs.
Then edit it.
>Show that any stress-energy tensor derived from a field Lagrangian will satisfy the conservation law.
pls help senpai
>>8079654
>taking it literally
ffs
>>8075006
y=x^y; lny=y*lnx
1/y=lnx+y*dx/dy*1/x differentiating both sides with respect to y
dx/dy=y^(1/y)*(1/y^2-(lny)/y^2)
=> y=e if dx/dy=0
Or x=e^(1/e)
>>8080384
What's the probability for no rain in the weekend?
>>8080416
Dude I already answered your question in another thread
P(norain)=1-P(rain)
I need some help with a probability question.
There is a pool of 94 questions.
every time i take the test, i randomly get 10 of the 94 questions.
how many times do i have to take the test to be 95% sure I've seen all the questions at least once?
what if i wanted to be 90% sure?
>>8080401
1) construct the canonical stress-energy tensor and see its divergence vanishes--genuinely don't remember if this is identically or pulling in the EOM
or
2) take a closer look at the conserved current associated with spacetime translation invariance
>>8080419
But what is P for norain then?
>>8080422
The canonical tensor is often not symmetric in 2 indices and violates conservation of angular momentum and even when symmetric can give different localization of of stress and energy than the Lagrange function of the field.
Can you derive the speed of the big bang from the beginning to the end of the inflationary period if we know the rough volume and the timeframe?
Or is it a nonsense question because it was an expansion of space and can't be quantified in such a manner?
How hard is it to get a degree in chemistry? Is it harder than chemical engineering?
I'm currently in my second year of chemical engineering but I actually wanted a degree in chemistry but my dad wanted me to study an engineering but he's dead now so whatever, what do?
>>8081720
Complete your chem eng degree then take a PhD in chemistry.
>>8081727
Thanks based anon
>>8081741
I'm curious though: what do you want the chem degree for? Research purposes?
>>8081750
I want to do research in organic chem
>>8081751
Yup, then it's perfect for you.
Cheers and good luck.
Prove that there are infinitely many values of n for which φ (n) = (1/2) * n − 1.
Got no idea. I tried carmichael function, eulers tuotient, proof by contradiction, ..., etc. I'm sure you guys would find it really easy...
Can anybody explain the first part of this question? It seems either way too easy or I'm terribly wrong
>>8082434
it IS easy, there is no hidden difficulty here.
>>8082212
if n= 2*p where p is an odd prime number, then according to https://en.wikipedia.org/wiki/Euler%27s_totient_function#Divisor_sum
(whatever it is called)
you have:
phi(1)+phi(2)+phi(p)+phi(n) = n
phi(1)=1
phi(2)=1
phi(p)=p-1
phi(n) doesnt' matter.
Now plug in:
2+p-1+phi(n) = n
so phi(n) = (n-p)-1 = p-1 = n/2 - 1 since n=2p.
as there are infinitely many odd primes, there are infinitely many values for n.
>>8082463
OK, thanks.
![K-Project 02 Kitten.mkv_snapshot_08.21_[2016.02.17_12.10.56].jpg](https://i.imgur.com/qrcdrqs.jpg "K-Project 02 Kitten.mkv_snapshot_08.21_[2016.02.17_12.10.56].jpg")
Im self studying Calculus II, specifically integration by parts, and I can't find any word problems online. Does this mean I don't need to learn how to do integration by parts with word problems, or that its just hard to find word problems? If the latter, where can I find some word problems?
Any help would be great.
>>8082629
I really don't see what the last hypothesis does.
>>8082636
Exactly, it seems so obvious but we are supposed to give a direct proof and I don't know how to go about it.
>>8082636
It is absolutely necessary though. For example consider the function given by [math]\frac {xy} {x^2+y^2}[/math] when [math](x,y)\neq (0,0)[/math]
and 0 elsewhere. This is continuous in the x and y directions but if you take the limit to 0 along the line x=y you get 1/2, so it is not continuous.
>>8082652
As I said, I don't know what it does. I know the first two are not sufficient, but I can't see why this makes it enough.
>>8082652
So any tips for writing my proof?
>>8082655
the only thing I see is that the partial function of the second variable is bijective... Still trying to see what it means.
>>8082629
all you have to is sub the R1 for R2 and there's your answer, trust me, i'm a philospher
How likely is it that two people with the exact same DNA by sheer coincidence (not identical twins or close family members) are alive today?
You'd think it would be very unlikely but then again it becomes a kind of birthday problem with 7 billion + individuals involved so could it actually be more likely than you would think? But I have no idea how many possible combinations of DNA exist that would still qualify as a human either, it could be too absurdly large for it to matter...
>solve for x
>10x-2z=3z
>add 2 to both sides
>10x=-5z
>divide both sides by 5
>2x=z
add -2 to both sides
>x=-2z
Where did I go wrong /sci/?
Please explain it to me like i'm 5.
I have not done algebra in years.
>>8082761
>10x-2z=3z
>10x=-5z
>2x=z
>x=-2z
>>8082761
10x-2z=3z
what does "add 2" mean to you?
maybe you meant "add 2z" to both sides.
10x-2z+2z = 3z+2z
which can be rewritten as
10x = 5z
Now you want to divide both sides by 5, you've done it correctly.
You're left with 2x = z
then
>add -2 to both sides
that's not what you did.
if you add -2 to both sides, you end up with 2x-2 = z-2
What you wanted to do is divide by 2 on both sides.
x=z/2
>>8082774
Thank you I see what I did wrong now.
Is there a name for problems like this?
I tried googling for rational expressions problems (what the professor called them in class) and ended up with x^2+2x+3/8+x problems.
>>8082784
I believe this is algebra in english
you should try these, in order
http://www.shmoop.com/basic-algebra/solving-one-step-equations-exercises.html
http://www.shmoop.com/basic-algebra/solving-two-step-equations-exercises.html
http://www.shmoop.com/basic-algebra/solving-complex-equations-exercises.html
everything comes from this
sitehttp://www.shmoop.com/basic-algebra/exercises.html
>>8082629
To prove that [math] f[/math] is continuous you have to prove it's continuous in every point
[math] (x_0, y_0)[/math] .
To prove it's continuous in that point you take an arbitary sequence
[math] (x_n,y_n) [/math] that converges against
[math] (x_0,y_0) [/math] and show that
[math] \lim_{n \to \infty} |f(x_n,y_n) - f(x_0,y_0)| = 0 [/math] .
In Analysis you always have to use the triangle inequality for stuff like that:
[math] |f(x_n,y_n) - f(x_0,y_0)| \leq |f(x_n,y_n) - f(x_0,y_n)|+ |f(x_0,y_n) - f(x_0,y_0)| [/math]
Now (i) already tells you that [math] \lim_{n \to \infty} |f(x_0,y_n) - f(x_0,y_0)| = 0 [/math] so you really only have to look at the other term.
Since [math] (x_n,y_n) [/math] converges against [math] (x_0,y_0) [/math] the sequence is bounded and you can find an interval [math][a,b] \times [c,d] [/math] such that [math] (x_n,y_n) \in [a,b] \times [c,d] [/math] for all [math] n [/math].
Consider the family of functions [math] h_n : [a,b] \to \mathbb{R} [/math] with [math] h_n(x) = f(x,y_n) [/math]. Those functions are continuous by (ii) and they are unformly bounded since [math] |h_n(x)| = |f(x,y_n)| \leq \max_{x \in [a,b]} \{f(x,d),-f(x,c) \} < \infty [/math] for every [math] x \in [a,b] [/math].
By the theorem of Arzela-Ascoli is the family (h_n) equicontinuous which is what you need.
![Dollarphotoclub_77959340-1024x577[1].jpg](https://i.imgur.com/CBkFpHm.jpg "Dollarphotoclub_77959340-1024x577[1].jpg")
>>8082789
Are chemist able to order illicit chemicals?
Is there any difference between [math]\sum_{i} x_i y_i[/math] and [math]\sum_{i} x_i \sum_{i} j_i[/math]?
>>8083038
meant
[math]\sum_{i} x_i y_i[/math] and [math]\sum_{i} x_i \sum_{i} y_i[/math]
>>8083042
take x1 x2 y1 y2 and expand both expressions. You'll see how different they are.
>>8082979
Yes.
My department's new assistant professor found a 5g bottle of fucking meth in a stockroom from years ago
She called the DEA to cart it off
Sigma aldrich is way cheaper than your dealer
>>8083038
let i=2
The first term is [math] x_{1}y_{1}+x_{2}y_{2} [/math], the second is [math] (x_{1}+x_{2})(y_{1}+y_{2}) [/math]
It's kinda the same reason (x+y)^2=/=x^2+y^2 in general
To learn calculus 1 and 2, do I need to learn llnear algebra first?
>>8083374
Thank you.
Is it normal that I find normal math problems pretty easy but word problems really hard?
Does that mean studying engineering would be a bad idea for me?
Or can I get good at them?
>>8083365
No but learn linear algebra first cuz it's way cooler.
>>8083402
It is too late, I bought lessons at udemy for calculus one and two. But of course I am planning on learning linear algebra, so I won't dissapoint you :^)
>>8073871
there u go
4th row - shouldn't the (H H+T) be the other way around? i.e. (H+T H)
and secondly.. how does it get reduced in the next line?
how can i be certain that theta runs from zero to 2pi?
>>8082629
You can prove this with a proof by contradiction. If The function is not continuous at f(x_0,y_0), then you can construct an infinite sequence {x_n,y_n} such that f(x_n,y_n) is always larger than f(x_0,y_0)+e_0 (if this isn't true for f(x,y), then it will be true for g(x,y)= -f(x,y)) and is located in an upper plane quadrant, and which converges to (x_0,y_0) monotonically. There exists a point f(x_0,z_0) which is less than f(x_0,y_0)+e_0, but the continuous function on the straight line with endpoints (x_0,z_0) and (u,z_0) either has a removable discontinuity, or an oscillation discontinuity because it must contain points greater than f(x_0,y_0)+e_0 because of the infinite sequence {f(x_n,y_n)} and the function's monotonicity with respect to the y axis. The contradiction is found, so the assumption that f isn't continuous is false.
>>8083806
Never mind I think it simplifies with the other combination at the end that goes outside of the integral cause it has no [math]\theta[/math]
>>8070803
Is it possible to find the rate of heat transfer by conduction of a rod if you only have the diameter, length and the temperature at either side? I dont have the thermal conductivity so i cant use pic rel formula
How does he get from the line 3 to 4?
What the fuck does the [math] ^2 [/math] mean in trigonometric identities?
For instance [math] cos^2 \theta [/math]
>>8084260
cos(theta)*cos(theta)
My sister says she sometimes sees shadows. Is she crazy?
>>8084290
that's what he just said you retard
>>8084315
This is some nice trolling bruv
Doing some online class work.
What are these symbols?
>>8084674
that's a zero (0) and the other one is a two (2)
ceiling
>>8084674
Ceiling function. ⌈x⌉ is the smallest integer greater than or equal to x. So ⌈0⌉ = 0 but ⌈0.1⌉ = 1.
>>8084776
Very cool, thank you for the information :)
How would one go about proving this by induction?
i've worked out that for n =0, b = 0.
However, i don't know how to approach the induction.
How do I into mathematical intuition?
How do I get laid?
Can someone explain me the Gaussian function a bit? I somteimes see it as
[eqn]\frac{1}{sqrt{2\pi\sigma^2}}e^{-\frac{|x-x_{c}|}{2\sigma}}[/eqn]
and sometimes it's just
[eqn]e^{-\frac{|x-x_{c}|}{2\sigma}}[/eqn]
What's the difference and why is this difference happening? People say nothing else than "assuming Gaussian" and then use one without further explanations
>>8084822
The above differs only by that one factor [math]\frac{1}{\sqrt{2 \pi \sigma^2}}[/math]. This is to normalize the function so that the integral over all x equals 1, which you want if you gaussian is a probability distribution.
>>8084842
Oh, that clears things up. Is this both for integrals and sums (discrete probabilities)?
>>8084849
For discrete probabilities your normalization factor would probably be something like [math]Z = \sum \limits_i exp({-\frac{(x_i-x_c)^2}{2 \sigma^2}})[/math], such that the probability for a single event j is [math]\frac{1}{Z}exp({-\frac{(x_j-x_c)^2}{2 \sigma^2}})[/math]. Of course if you sum over all possible events you see that it's again normalized to 1.
>>8084849
>>8084860
And to add, it's the same thing yeah pretty much. In the case of discrete probabilities the normalization factor is the sum of all those exponentials, in the continuous case it becomes the integral over all those things. It so happens that [math]\int \limits_{-\infty}^{\infty}exp(...) = \sqrt{2 \pi \sigma^2}[/math] so you divide by that to obtain something normalized to 1.
If that makes any sense.
I'm terrible at integration by parts, what do I do if it doesn't start with x?
The first question on it was to integrate x e^4x dx, which was simple enough if xe^4x/4 - e^4x/16 + C is the right answer, but I can't see an obvious way to make the technique work if I can't simply make u = x, such as in the case where I have to integrate x^2 e^-3x dx
>>8084903
When it comes to integration by parts ask yourself "Does the integrand become simpler when I differentiate it?". So in this case you might notice that if you pick [math] u = x^2 [/math] then when you differentiate it you get an integral that looks a lot like your previous question.
>>8084903
sometimes you need to do multiple integrations by parts one after the other.
what I like to do is put the two functions in two columns.
Then in each row, I differentiate one function and integrate the other one.
And keep doing that until I'm satisfied with what I have in one row.
For example in x^2exp(-3x)
x^2 \ exp(-3x)....................+
\
2x\ \-exp(-3x)/3.................-
\
2 --- \ exp(-3x)/9...................+
I drew three arrows: two diagonal arrows and one horizontal arrow.
I also added alternating + and minus signs for each line, starting with +.
FOR EACH DIAGONAL ARROW: you compute the result.
example if you want to integrate x^2*exp(-3x) between 0 and t, you will get:
[math][-x^2 e^{-3x}/3 - 2x e^{-3x}/9]_0^t = -t^2e^{-3t}/3 - 2te^{-3t}/9[/math].
Now you always have one horizontal line. This is what will be under the integral.Don't forget to add the corresponding sign, here it's a +.
[math] + \int_{0}^t 2 e^{-3x}/9 dx [/math]. This integral is easy to compute. [math]-2 e^{-3t}/27 + 2/27 [/math]
In the end, you just sum everything, you get [math]2/27 - e^{-3t}/27 (9t^2+6t+2)[/math].
Hope the layout comes right. I'll send a picture otherwise.
>>8084913
As expected, the layout is crap.
Read post with this pic pls
Can anyone explain why
>i/i = 1
>>8084936
I don't understand why it's a problem or what there is to explain.
>>8084939
so 0/0 = 1 as well? thanks, I knew it!
>>8084939
>Anything divided by itself is 1.
>Any number is that number of ones, even i; so if it divides by itself, it leaves only ones behind.
Thank you, I got so focused on i being square root of negative 1 that I forgot that simple rule of mathematics.
>>8084946
No, % is clearly 1/100.
If you're converting a CFG to CNF, would this be correct?
D->DAB | empty string
A->a
B->b
D->CAB
C->AB
A->a
B->b
or am i fucking it up when the CNF can't create a string "ab" now?
>>8084946
Yep, write [math] y = x^x [/math] then [math] \ln (y) = x \ln ( x ) [/math]. Observe that if we agree to keep [math] x [/math] small then [math] 0 < \ln (x) < 1[/math] from which it immediately follows [math] 0 < x \ln (x) < x [/math] now taking the limit as [math] x \to 0 [/math] tells us that [math] x \ln ( x ) \ to 0 [/math] as well, thus we have [math] \ln (y) = 0 [/math] from which we get [math] y = 0^0= 1 [/math].
>ezpz.
I know that [math]\frac{∂z}{∂x}[/math] can equal [math]\frac{∂z}{∂t}·\frac{dt}{dx}[/math]. But can it also equal [math]\frac{∂z}{∂t}·\frac{∂t}{∂x}[/math] or [math]\frac{dz}{dt}·\frac{∂t}{∂x}[/math] depending on the circumstances?
>>8085121
>LelTeX
Why am I not surprised. Reposting.
I know that \frac{∂z}{∂x} can equal [math]\frac{∂z}{∂t}· \frac{dt}{dx}[/math]. But can it also equal [math]\frac{∂z}{∂t}· \frac{∂t}{∂x}[/math] or [math]\frac{dz}{dt}· \frac{∂t}{∂x}[/math] depending on the circumstances?
>>8085124
Okay. That was my mistake this time. But screw it.
>>8085125
It was your mistake both times faggot
the tags need those spaces to parse
>>8085183
>the tags need those spaces to parse
Not in the previewer they didn't. That means it's the problem with /sci/'s LaTeX.
>>8085195
>[blaming others intensifies]
>>8085250
Go to bed Hiro, you're drunk.
>>8084795
10^{n+1}a=(9+1)10^na.
Now use your IH and algebra
>>8085121
You know you don't need to actually use the ∂ symbol, you can just use \partial. Same for \cdot for the dot, but in your situation I'd just concatenate, like this: [math] \frac{\partial z}{\partial t} \frac{dt}{dx}[/math], otherwise it looks like you're taking the dot product.
Using the 4chan TEX preview seems to cause it to stop working, which is why even though your text is formatted properly it isn't showing up (that or it dislikes your ∂ symbols!).
>>8085303
I know of \partial and \cdot but I prefer using ∂ and · respectively because using the symbols makes the whole code much simpler. The only exceptions are symbols like \ which will make the whole code not work unless you use \backslash instead. { will also ruin the whole code unless you use \lbrace or \{ instead. Same for }. So far I've only encountered these 3 exceptions.
I have no problem whatsoever using ∂ even in /sci/s LaTeX but it's still wonky compared to the previewer's LaTeX where some parts of the code need spaces in between them for them to work in /sci/'s LaTeX when they don't need it in the previewer's LaTeX. Thing is finding these cases requires trial and error, and I just stumbled on one, where · needs a space after it if there's a symbol in code form right after the dot. But yeah you might be right about not using the dot, I'll drop it next time.
Maybe I should create a LaTeX thread for this.
who was that one famous mathematician with the "i mean seriously top-shelf stuff" quote?
>>8085357
Feynman? He was a physicist.
>>8085351
>I know of \partial and \cdot but I prefer using ∂ and · respectively because using the symbols makes the whole code much simpler
Why are you bothering to use LaTeX at all if you're not going to take advantage of the symbols?
How are these 2 equal? To me it looks like one is a and the other one is -a
What does this mean?
>>8085381
I still need it to show shit like fractions too.
>>8085385
if you revert both the numerator and the denominator, you still get the same thing.
>>8085386
This is basic inter universal teichmuller theory. See mochizuki's papers, he explains everything there.
I'm coming up with nonsense here.. I seem to be finding the minimum speed, not the maximum.. and a fictional minimum at that (0). Any pointers? I'll upload my working in a sec
>>8085495
1/2
>>8085503
2/2
How can I move a point a certain distance along an arbitrary vector?
is brilliant.org a good website to become apt in simple mathematics? I'm out of school and just want to increase my abilities
>>8085729
why not khan
>>8085732
brilliant has a lot more interactive quizzes and a smarter ranking system. Theres also many sub categories for maht
>>8085729
Most of it is far too easy and tests knowledge of the same handful of tricks over and over.
If it challenges you, you're growing mathematically which is good. But you won't get very much mileage out of it
Shouldn't it be y = 3x?
If for every adult dinosaur there are 3 baby dinosaurs...
pls help
>>8085826
When x is the number of babies and y the number of adults, your equation means "The number of adults is equal to three times the number of babies."
Maybe you see it now.
>>8085826
Try to plug in values and see what happens. If there are 3 baby dinos (x=3), what is y equal to? 1 or 9?
y=3x says the opposite, that y, the number of adults, is three times x, the number of babies
x=3y is correct.
Found this for free at my math department. Should I know anything before attempting to work through it?
>>8085897
No idea of the quality of the text, but it sure looks pretty.
If you want to express the sentence "For every 13 seats in economy class, there are 5 seats in business class." algebraically, why would it be [math]e/13 = b/5[/math]?
I just don't get it.
>>8086152
yes
as I told someone earlier for something similar: just plug in some values you know to work to check.
if you have 13 economy class seats, you have 5 in business.
so if e=13, b=5
does that work with e/13 = b/5? yes.
>>8086161
I'm the same guy haha
>tfw struggling with middle school math problems
but that makes sense, thanks man. sometimes I just have trouble visualizing what the math means.
>>8070803
Is anyone here studying a bachelor/doctor of medicine/surgery?
Would you say the passing the exams is more or less difficult than gaining entry into the course in first place?
>>8083393
You can get good anon. Draw pictures
>>8070803
if anyone can answer as fast as possible please, i have a really bad toothache and cant get to the emergency treatment until tomorrow in 7 hours
i have diclofenac at hand but its not helping, how much can i take without accidentally killing myself?
Can someone explain homogeneous functions and how to integrate first order homogeneous functions with substitution. Also please explain the differences between the f(xt,yt)=t^a(f(x,y)) vs. getting it into the form of y/x
What's the most rigorous linear algebra book? Would be a nice bonus if it also has autistic tier problem sets.
>>8084795
10 = 1 mod 9, so (10^n-1) a = 0 mod 9.
I think a can be any integer
I would like some help finding the area enclosed by the equation and the x-axis. I faintly remember something about integrals...
But why?
How do I solve:
[eqn](x^2-1)*cos(x)+4x=0[/eqn]
I would appreciate some help because I seem to be stuck and have already tried everything I can think of.
>>8086911
wanna know a funny thing? I got three poor hairs on my right thumb, but none on my left
interested in this as well.
>>8086941
what makes you think you can solve it?
>>8086946
Not him but even if it can't be solved algebraically numerical techniques should work.
>A DFS greedy vertex coloring algorithm will provide the optimal coloring for any connected graph.
>Optimal coloring means it will use the least amount of colors.
>DFS with backtracking
What is the counter example to this?
Is there anything worse than people who claim "black is not a colour"?
Fair enough if it's a scientific discussion about the properties of light and colour, but I'm talking about shit like:
>Hey what's your favourite colour ?
>Black.
>Ermmm, I think you'll find that black is NOT a colour
>>8086946
I know that these type of problems are very rarely solvable.
But it is part of a task I have and it explicitly states that no numerical techniques should be used.
I figured there is some clever kind of substitution but I tried everything I can think of.
You can rewrite it to
[eqn]\frac{cos(x)}{2*tan(atan(x)*2)}=1[/eqn]
but even that doesn't help.
>>8086952
Does it really say solve or does it just say to prove that there is a solution?
>>8086953
The Questions is kinda ambiguous and the Problem is a Part of a bigger question about extreme points of a functions.
I located the other extrema easily and especially the part about "no numerical techniques" made me think that there was a trick I was missing and locating the points was part of the task.
Proving the existence of a solution is not hard and that is probably what I will go with.
Anyway, thanks for your time.
I have to do a 3 month biology and chem (A level equivalent) course because i only took humanities in HS.
Are there any good textbooks out there?
Does /sci/ support Trump or Clinton?
>>8083808
this?
can the roots of a polynomial with complex coefficients occur in conjugate pairs? appeared on algebra test yesterday. i think its false
>>8086970
neither.
Does Faà di Bruno's formula work with Itô's Lemma?
>>8086981
roots can be anything, e.g. f(z)=i*(z-i)(z+i)
>>8086941
chances are you've made a mistake earlier. solving an equation with mixed trig and polynomial terms and rational coefficients is typically impossible explicitly. You have a hope x=0 will work, but that's about it.
>>8086981
I don't get the question either. Do you mean a polynomial of even degree?
What's the normal thing these days for people doing maths in Universities?
I did my degree long before tablets were much of a thing. You could technically drag a laptop around but a normal person just had a notepad.
I can't imagine in 2016 sitting down writing page after page with a pen and paper. Nor could I imagine trying to keep up with some professors scribbles using any form typing, once you deal with all the symbols people use.
>>8087155
pen and paper.
If you are lucky, the prof will put notes online and you can just print them and add your personnal notes on them.
Is there something wrong with this integration by parts plus u-substitution? after I make it the integral comes out wrong (I have the solution). Any Ideas?
>>8087155
>I can't imagine in 2016 sitting down writing page after page with a pen and paper.
I can't imagine why you would feel this way. Paper is far from obsolete.
When it says spectral radiance, I know the units used but can someone explain it to me like the idiot I am?
>>8087194
It seems that you missed a minus sign when calculating dt/dx
>>8087225
the density of power per unit of surface for each wavelength.
Basically it's the contribution of each wavelength of emmited radiation to the total power.
Why do psychology majors get so upset and instantly resort to ad homiem responses when you inform them that psychology isn't a science?
>>8087273
I got a better question: why do you bother people?
I bet you're the kind of guy who thinks he's smart but somehow can't get a gf.
>>8087276
Becacuse I find it interesting that some people can argue with such fervor and yet refuse to present a logic based answer, rather responding with something similar to "I bet you're the kind of guy who thinks he's smart but somehow can't get a gf."
