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grrid problem by Fanny Bleblingbone - Wed, 16 May 2012 20:07:21 EST ID:KZ+bYB/3 No.8406 Ignore Report Reply Quick Reply
1337213241435.png -(28613 B, 320x320) Thumbnail displayed, click image for full size. 28613
This is probably something anyone who didn't sleep through high school math could answer. I need a way to convert positions on the grey grid into positions on the red grid, which could potentially be at any angle and position at all ever.
>>
Sidney Chuvingfatch - Wed, 16 May 2012 20:37:51 EST ID:ufNhuFq9 No.8407 Ignore Report Quick Reply
Use linear transforms. Scaling, translation, and rotation, in particular. It's a matrix multiply to go from one coordinate space to another once you plug in all the parameters.
>>
Sidney Mabberridge - Thu, 17 May 2012 16:07:55 EST ID:srBptOIC No.8408 Ignore Report Quick Reply
you learned this in high school? lucky fuck i had to take a university course to know how to do that. fuckin north america


finding bigger primes by Clara Hicklebet - Wed, 02 May 2012 20:13:08 EST ID:9vixduEX No.8259 Ignore Report Reply Quick Reply
1336003988554.jpg -(46102 B, 636x477) Thumbnail displayed, click image for full size. 46102
2x3=6. 6+1=7
2x3x5=30, 30+1=31
2x3x5x7=210, 210+1=211
2x3x5x7x11=2310. 2310+1=2311

7, 31, 211 and 2311 are all primes. This keeps producing prime numbers as it continues. (yes the general proof exists)

I had heard finding big prime numbers is quite a task and a new one isn't found too often. theres a world record and all.

However, it seems like using the pattern above it should be quite simple to find new primes. (as computers are able to multipy huge numbers. (they are right?)). Where am i wrong? why isnt it really easy to find new primes if all you have to do is multiply all the primes we know and add 1?
15 posts omitted. Click Reply to view.
>>
Ernest Chuggleridge - Thu, 10 May 2012 14:54:06 EST ID:+5QIUVXO No.8355 Ignore Report Quick Reply
hitler will rise again and the universe will turn inside out
>>
Name - Thu, 10 May 2012 19:10:54 EST ID:V0N1pobx No.8357 Ignore Report Quick Reply
>>8355
oh how i do look forward to the 2nd cuming of christ
>>
Polly Tillinggold - Fri, 11 May 2012 03:15:44 EST ID:Lfp6BgAH No.8363 Ignore Report Quick Reply
>>8259
If this proof is the one I am thinking of then the conclusion has a catch. You can say one of these things about your number you just made:

  1. it is prime
OR
2. there was a prime we did not account for which can divide it.
>>
Ferp Rickelderp - Fri, 11 May 2012 03:36:59 EST ID:70Fjp38W No.8364 Ignore Report Quick Reply
>>8363
example?
>>
Simon Himblesid - Wed, 16 May 2012 18:55:12 EST ID:aXFn0F2S No.8405 Ignore Report Quick Reply
6n + 1 = prime number.


Golden Ratio by Reuben Pockstone - Sat, 12 May 2012 15:41:50 EST ID:reri5G6g No.8373 Ignore Report Reply Quick Reply
1336851710035.png -(28350 B, 808x423) Thumbnail displayed, click image for full size. 28350
I'm not good at maths so go easy on me. I'm a musician interested in using the golden ratio in my pieces.
Reading about the golden ratio, I often see the concept of a+b=c highlighted. However if you split a line into two parts, of course the two parts are going to add up to form the whole. If you have a line that is 8cm split into two sections of 2cm and 4cm:
4/8 = 0.5
2/4 = 0.5

So the real deal about the golden ratio is that the ratios approximate phi? I just found it strange that the above concepts are stressed so heavily (a/b=b/c)
when they could be applied to many other shapes/ratios that aren't the golden ratio. I'm obviously missing something, so can anyone clarify?
>>
Eugene Boddlefuck - Sat, 12 May 2012 18:51:59 EST ID:AnBeLn0m No.8376 Ignore Report Quick Reply
The ratio thing is an issue of self similarity.
If you take any two successive line segments l, m and (l+m), where m/l is the golden ratio, (l + m)/m is also the golden ratio.
If you try it with line segments 2 and 4 cm long, 4/2 does not equal (2+4)/4.
Infact, that relation can be used to derive it, which shows that it's the only number that satisfies the condition.
(l + m)/m = m/l
l/m +m/m = m/l
l/m +1 = m/l

substitute m/l = x, l/m must equal 1/x
1/x + 1 = x
1 + x = x^2
0 = x^2 -x -1

Applying the quadratic formula, where a, b and c are the coefficients of the terms, thus 1, -1 and -1 respectively
x = -b/(2a) +/- sqrt(b^2 -4ac)/(2a)
Comment too long. Click here to view the full text.
>>
Jenny Funderstone - Sat, 12 May 2012 19:11:11 EST ID:uBfbMqCl No.8378 Ignore Report Quick Reply
>>8373
This book may be of help; its informative and not very math intensive.
http://www.amazon.com/The-Golden-Ratio-Worlds-Astonishing/dp/0767908163
>>
Caroline Buzzford - Sat, 12 May 2012 19:14:45 EST ID:jhdm5dHC No.8379 Ignore Report Quick Reply
>>8373
To put it more simply for you, non-math guy:
First of all, you can't split an 8cm segment into to other segments of 2cm and 4cm.. because then you'd still have a third segment of 2cm. (4+2=6, not 8)

The thing about the golden ratio (among a huge amount of other things) is that if you have a given segment of C lenght, then you can split it into to other segments, A and B (A+B=C!!) with A<B, then
B/A = C/B
If that happens, then
A*phi = B
B*phi = C
With phi being the golden number.
(Also, for each given segment, there is one and only one way to split it into two smaller segments so that the above thing happens)
>>
Simon Himblesid - Wed, 16 May 2012 18:52:10 EST ID:aXFn0F2S No.8404 Ignore Report Quick Reply
>>8376
Only if l=0 would that make sense, and we all know what happens if you were to successfully divide by 0... Black holes and such. the whole golden ratio notion should be banned from thought.


stats by Graham Foblingforth - Wed, 16 May 2012 02:14:56 EST ID:MQ2Ptc41 No.8400 Ignore Report Reply Quick Reply
1337148896524.jpg -(105542 B, 800x600) Thumbnail displayed, click image for full size. 105542
People randomly return block to 4 large baskets. Find the probability that exactly 5 blocks are returned to each basket if there are 20 blocks.
>>
Fuck Cronningkidging - Wed, 16 May 2012 07:26:42 EST ID:r62S1/// No.8401 Ignore Report Quick Reply
1 : 20^5

or 1 : 2000000?
>>
Molly Cicklewere - Wed, 16 May 2012 08:49:37 EST ID:l1meLf61 No.8402 Ignore Report Quick Reply
>>8400
243/33554432
>>
Hamilton Hebbercocke - Wed, 16 May 2012 17:56:02 EST ID:ufNhuFq9 No.8403 Ignore Report Quick Reply
1337205362403.gif -(951 B, 113x42) Thumbnail displayed, click image for full size. 951
combinatorial!


Let statements. by Augustus Fanspear - Tue, 15 May 2012 16:45:46 EST ID:FWoa+Cip No.8396 Ignore Report Reply Quick Reply
1337114746632.jpg -(26590 B, 400x290) Thumbnail displayed, click image for full size. 26590
So, you are all good at equations and let statements.
Answer a few of these I came up with.

1.
V=lwh, find w when V= 72yd^3, l=0.75, and h=12yd.

2.
If I=prt, find the principal, p, when the interest, I, is $135, the yearly rate of interest, r, is 2.5%, and the time, t, is 3 years.

3.
If T=nc, find the number of items purchased, n, if the total cost, T, is $19.80 and the cost of one item, c, is $4.95

4.
If S=nw, find the number of hours worked, n, if S=$315.00 and w=$8.40
Comment too long. Click here to view the full text.
>>
Betsy Gubbletutch - Tue, 15 May 2012 17:29:51 EST ID:zj4pWrXX No.8398 Ignore Report Quick Reply
  1. V=lwh, find w when V= 72yd^3, l=0.75, and h=12yd.

72 = (.75)(12)(w)
72 = 9w
8 = w

fin
>>
Jenny Penningwick - Wed, 16 May 2012 01:51:00 EST ID:NUXuTEs/ No.8399 Ignore Report Quick Reply
Number 1:
72yd^3 = lwh
= (0.75)(12yd)w
w=72yd^3/(0.75*12yd)
= 8d^2

Number 2:
L=prt
p = L/(rt)
= $135/(0.025*3 years)
= $1800 per year

can't be bothered with any more.


FRACTALS by Lynda - Tue, 08 May 2012 01:24:51 EST ID:ysh/BNhL No.8322 Ignore Report Reply Quick Reply
1336454691837.png -(55423 B, 600x600) Thumbnail displayed, click image for full size. 55423
/MATHS/

tell a really un-mathematical person about fractal patterns please, Ifind them fascinating, yet I cannot into them.

Also, any good books on them with lots of pictures, I like pictures.
10 posts and 2 images omitted. Click Reply to view.
>>
Ferp Rickelderp - Mon, 14 May 2012 22:18:05 EST ID:70Fjp38W No.8390 Ignore Report Quick Reply
>>8385
It's a julia set of the burning ship fractal z(n+1)=(abs(Re(Z(n)))+i*abs(Im(Z(n))))^2+C but i don't have the exact coordinates saved, if that's what you're asking.
>>
Lynda - Tue, 15 May 2012 00:35:39 EST ID:ysh/BNhL No.8391 Ignore Report Quick Reply
>>8385

Oh, thank you.
>>
Fucking Pockhood - Tue, 15 May 2012 01:26:10 EST ID:YDu+jK6j No.8392 Ignore Report Quick Reply
since we're posting fractals...
This one's different from most stuff you'll see - it has more to do with interference patterns.

http://www.youtube.com/watch?v=gj6i1K50aOY&
if the intro is boring skip to about 3:30
>>
Charlotte Fuckingson - Tue, 15 May 2012 14:59:47 EST ID:sPd/0oB/ No.8395 Ignore Report Quick Reply
>>8390
Alright, thanks. I didn't know this fractal.
It seems this picture had post-processing. Do you used a software, or did you make the picture yourself ?

I'm actually very interested about fractal rendering, because I'm probably going to present fractal art at an art expo.
I may have to make a thread on this boards one day, asking for interesting fractals to show to people.

>>8391
You're welcome. If you like computer science oriented art, you should also check out cellular automatons (CHAOS EVERYWHERE).
http://www.youtube.com/watch?v=1XOjUz8cQYU this one is cool
>>
Ferp Rickelderp - Tue, 15 May 2012 17:15:09 EST ID:70Fjp38W No.8397 Ignore Report Quick Reply
1337116509115.png -(375190 B, 1596x794) Thumbnail displayed, click image for full size. 375190
>>8395
I rendered it with Fraqtive, which is free software. The formula i used is one of the built in options. The only post processing i did was converting the original 30mb png image to a jpg small enough to upload. FractalForums.com is also a good resource. I agree cellular automata are interesting, here's a 2d automaton i made in MatLab with a spiral weighted modulo loop.


kernls by Angus Blindledodge - Tue, 15 May 2012 12:36:16 EST ID:wzdnTFUX No.8393 Ignore Report Reply Quick Reply
1337099776680.gif -(1382855 B, 650x650) Thumbnail displayed, click image for full size. 1382855
Are there any examples of transformations/functions where the kernel is a function of the limits of integration?... hm


MacroEconomics by Ebenezer Tillingdock - Mon, 14 May 2012 18:40:34 EST ID:YWSZNvh5 No.8386 Ignore Report Reply Quick Reply
1337035234041.jpg -(22042 B, 250x307) Thumbnail displayed, click image for full size. 22042
Okay, guys. Starting today, I'm taking Macroeconomics over the course of a two-week intersession class. I've already had Microeconomics, so I'm not TOTALLY 'tarded, but it has been a while and I'm not a math/business/econ major. Obviously, I'm really gonna have to work on this stuff to do well enough on my first week's midterm and second week's final to pass. Any suggestions for online help (websites, videos, blogs, whatever)?

THANKS!
>>
Fuck Chassleham - Mon, 14 May 2012 20:30:30 EST ID:SC8raZfn No.8387 Ignore Report Quick Reply
Is this introductory, or is it actual theory?

Intro level macro or micro is only babbymath. If you can do arithmetic and draw graphs, you're fine. Also, there's so much overlap between intro to micro/macro that you'll probably have very little work to do until he end of the course.
>>
Archie Greencocke - Mon, 14 May 2012 20:54:13 EST ID:YWSZNvh5 No.8388 Ignore Report Quick Reply
>>8387
Normally I wouldn't worry much, but since this is condensed into two weeks, I sort of am. Guess it's a little more than an intro class.. It's a 200 level course.


Yeah, man. by Samuel Grandridge - Fri, 11 May 2012 00:05:16 EST ID:I8Zkoa3j No.8361 Ignore Report Reply Quick Reply
1336709116589.png -(12722 B, 535x87) Thumbnail displayed, click image for full size. 12722
That is all.
1 posts omitted. Click Reply to view.
>>
Matilda Dillersadge - Fri, 11 May 2012 18:51:34 EST ID:fuxc93L5 No.8367 Ignore Report Quick Reply
Base prime FTW
>>
Cyril Drugglemutch - Fri, 11 May 2012 20:52:55 EST ID:KCZJSqcb No.8368 Ignore Report Quick Reply
balanced ternary master race
>>
John Brookshaw - Sun, 13 May 2012 16:58:41 EST ID:hIhAKnG5 No.8381 Ignore Report Quick Reply
'things that isn't'. oh god.
>>
Basil Sepperlock - Sun, 13 May 2012 17:05:05 EST ID:9wEeqLWL No.8382 Ignore Report Quick Reply
>>8381

The verb "is" agrees with the subject "way" in number. There's nothing grammatically incorrect about that.
>>
John Brookshaw - Sun, 13 May 2012 17:12:00 EST ID:hIhAKnG5 No.8383 Ignore Report Quick Reply
>>8382 Ah yes I just read it wrong


Simple 3d vector equations by Oliver Fabblefere - Sat, 12 May 2012 16:26:18 EST ID:obW3SSCt No.8374 Ignore Report Reply Quick Reply
1336854378423.jpg -(28087 B, 256x192) Thumbnail displayed, click image for full size. 28087
My library is shit for SIMPLE vector problems
I was wondering if you guys can help me out, I'm in the hardest maths course there is, and everything else is fine, but this shit, I just can't find anywhere.
So no need to give the answer, just point me in the right direction:

Find the equation of the line passing through the points:
(2,1,3); (1,2,-1)

I know to many this looks very easy, even to me, but I have no previous background in vectors
>>
Eugene Boddlefuck - Sat, 12 May 2012 18:06:07 EST ID:AnBeLn0m No.8375 Ignore Report Quick Reply
The direction vector going from between position vector p to the position vector q is q-p.
The line must consist of every scalar multiple of this direction vector, shifted by another vector mso as to be at that position when your variable is 0.

Hope that helps, trying not to spell it out too much.
>>
Caroline Buzzford - Sat, 12 May 2012 19:07:18 EST ID:jhdm5dHC No.8377 Ignore Report Quick Reply
P=(2,1,3)
Q=(1,2,-1)

Equation of the passing line:
L = t*(Q-P) + P (or +Q)
with t being any real number.
So, L = t * (-1,1,-4) + (2,1,3)
L= (-t+2,t+1,-4t+3)
>>
Ferp Rickelderp - Sat, 12 May 2012 20:20:05 EST ID:70Fjp38W No.8380 Ignore Report Quick Reply
1336868405964.jpg -(41276 B, 801x829) Thumbnail displayed, click image for full size. 41276
>>8374
>vector problem
>point me in the right direction
mfw


integral of position by Nathaniel Wundlehood - Thu, 03 May 2012 02:50:55 EST ID:SDTzDu1i No.8267 Ignore Report Reply Quick Reply
a(t)=f"(t) is undefined,
v(t)=f'(t)=0
p(t)=f(t)=1
And the integral of f(x)=x
P is postion, v is velocity, and a is accelerstion.
Velocity is the integral of acceleration and position is the integral of velocity, what is the integral of position? i know it is x and i can picture it as a graph, but what does it represent ? I can't wrap my head around the concept. I am really stoned and typing this from my smart phone. I tried making it as clear as I can.

What does the integral of position represent?
>>
Basil Drogglesat - Thu, 03 May 2012 03:36:58 EST ID:AnBeLn0m No.8268 Ignore Report Quick Reply
Provided you're talking about integrating with respect to time, that would appear to be 'absement'. There's not much documentation about it so I suspect it isn't very useful, google for a few pages.
>>
Eliza Niggerlock - Sat, 12 May 2012 13:48:36 EST ID:AV5IQ1ep No.8371 Ignore Report Quick Reply
Thanks for the reply, bumping for further discussion
>>
Charlotte Pabblewone - Sat, 12 May 2012 14:16:04 EST ID:R0WyIvJY No.8372 Ignore Report Quick Reply
If P(t) is a parametrized function representing the position vector then you could integrate over said function. This is usually called a line integral and can be used to find arc length of a curve in space, among other things.


Algebra Help by Hannah Murdwill - Tue, 08 May 2012 17:59:01 EST ID:Y5Xsbcjn No.8328 Ignore Report Reply Quick Reply
1336514341123.jpg -(209546 B, 982x1149) Thumbnail displayed, click image for full size. 209546
Assuming the math leading up to this part of my problem isn't wrong, I need help.

This expression is supposed to cancel itself out, but I can't wrap my head around how to do it. The original expression is (x / y)^1/2 + (y / x)^1/2 = 10

I'm trying to cancel out this: (y^(3/2) - x) / (x^(3/2) - y)
It's not homework or anything because I'm done calculus, I just don't want to leave a problem unfinished you know?
4 posts omitted. Click Reply to view.
>>
Martin Fubberhutch - Wed, 09 May 2012 12:26:37 EST ID:jhdm5dHC No.8343 Ignore Report Quick Reply
Also, I just realized you could there which much fewer steps.

In the inital equation just square both sides, and you'll get

x/y + 2 + y/x = 100
Then
x/y + y/x = 98

(It's the same i made before, but much shorter)
>>
Matilda Bullerset - Wed, 09 May 2012 16:25:04 EST ID:Y5Xsbcjn No.8344 Ignore Report Quick Reply
I think you might have misunderstood what I was trying to do. I don't need the original expression simplified, I'm just looking for some kind of proof that the expression below it is equal to 1. I'm not sure if it can be done, but apparently it is equal to 1, unless my previous work is incorrect.
>>
Martin Fubberhutch - Wed, 09 May 2012 16:41:54 EST ID:jhdm5dHC No.8345 Ignore Report Quick Reply
>>8344
I'm not quite understanding you.
You want a proof that
(y^(3/2) - x) / (x^(3/2) - y) = 1 ??

Well thats not true my friend, and here is a counter-example

Take the pair (x,y) = (1,0)
Put that in your equation, and you get = -1

Take another random pair, and you'll most likely get something different from -1.
(pair (2,1), for example).
So no, that expresion cant be canceled out, for it depends on which x and y you take.
>>
Frederick Mupperlock - Sat, 12 May 2012 08:00:19 EST ID:q6KdfXZb No.8369 Ignore Report Quick Reply
>>8328
Hi, I don't do pure maths so this might be *very* wrong, but its one solution at least. i.e there might be a lot more, infact due to using a square there'll be at least another one. I'm fairly sure if you play with it for a bit you'll be able to pull the others out.

as implicit probably makes more sense in polar co-ordinates therefore
define
y = r sin t
x = r cos t

dropping the t as its in everything (its still there just not writing it out)

sub into original:
sqrt(r cos / r sin) + sqrt( r sin / r cos) = 10
sqrt( cot) + sqrt (tan) = 10
square both sides and only consider one solution
cot + tan + 2 = 100
Comment too long. Click here to view the full text.
>>
Frederick Mupperlock - Sat, 12 May 2012 08:07:39 EST ID:q6KdfXZb No.8370 Ignore Report Quick Reply
>>8328
Ha, I spotted the trick way to do this whilst writing that brute force solution out. However you just have to 'see' these kind of substitutions in order to do stuff like this. So if this is some sort of exam I'd use polar co-ordinates whilst longer its a more reliable solution.

you're at the point
x/y + y/x = 98
sub t = y/x
t + t^-1 = 98
multiply through by t
t^2 -98 t +1 = 0
the roots to that are the two possible values of t.

since we've defined t = y/x then the two roots are two gradients i.e solutions are of the form y = tx
(noting that both roots are solutions so there are two lines so it will look like a cross on an xy plot)



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