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Old 12-01-2014, 12:56 AM   #9861
damian_91
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Quote:
Originally Posted by guitarplaya322
How do you solve this differential equation using separation of variables?

dy/dx=(-2y+x^3)/x

you can't write that as dy/dx=f(y)/g(x)

y'+(2/x)*y = x^2

multiply both sides by exp(*integral* 2/x dx), then you're left with d/dx (y*x^2) = x^4
then y*x^2 = 1/5 x^5 + c
y= 1/5 x^3 +c/x^2
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The truth is, Muslims never apologized for their faith having something to do with the attacks on 9/11.
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Old 12-02-2014, 07:28 PM   #9862
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what do the square brackets mean? just standard grouping i think

what does the dot mean in the right hand side of the third equation?

what is that triangle thing in the the fourth equation? explained in the text

first order logic apparently

taken from http://webdam.inria.fr/Jorge/files/wdm-ontologies.pdf
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Old 12-10-2014, 04:32 PM   #9863
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http://www.biostat.umn.edu/~brad/V9SingAlong.pdf
For those that like Bayesian statistics/econometrics and bad parodies.
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Old 12-19-2014, 06:51 PM   #9864
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To show that art and science can really come together in a purely aesthetic way:
http://www.histoservinc.com/photo/s...-1_edited-1.jpg

It's part of the gastrointestinal tract and I thought wow that looks amazing. Who will appreciate it. Hope someone out there has
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Old 12-20-2014, 08:10 AM   #9865
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OK so I understand the concept of a 'moment' in mathematics. But what exactly is an inverse moment? I have not yet found an answer despite my thorough search of the first page of google results.
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Old 01-04-2015, 09:22 PM   #9866
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guys quick question, I'm stuck on a very small part of Laplace transforms. Its not the Transform itself, its a small algebra thing in a part of the Transform

basically, why does (2/(s+4)) + 1 simplify to 2+(s+4) / (s+4)

is it because you have to make +1 into a fraction as well, and then make the denominators the same by multiplying in (s+4)?

i hate algebra sometimes
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Old 01-05-2015, 12:15 AM   #9867
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Quote:
Originally Posted by Bladez22
guys quick question, I'm stuck on a very small part of Laplace transforms. Its not the Transform itself, its a small algebra thing in a part of the Transform

basically, why does (2/(s+4)) + 1 simplify to 2+(s+4) / (s+4)

is it because you have to make +1 into a fraction as well, and then make the denominators the same by multiplying in (s+4)?

i hate algebra sometimes

1=(s+4)/(s+4)

2/(s+4) +1 = (2+s+4)/(s+4)
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The truth is, Muslims never apologized for their faith having something to do with the attacks on 9/11.
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Old 03-14-2015, 05:41 PM   #9868
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Happy Pi day
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Old 04-17-2015, 11:42 PM   #9869
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Did someone try to crack the "Cheryl's Birthday" thing yet?:

http://edition.cnn.com/2015/04/15/l...lem-goes-viral/

I haven't been spoiled about it, so I'll try. Seems similar to that "2-colored person island" logic problem.

show

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Old 04-17-2015, 11:44 PM   #9870
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Old 04-29-2015, 08:44 PM   #9871
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Hey guys, basically just want to sanity-check something here.

For the equation below, if t = 0, then the whole thing equates to 1, correct?

Either this is just me checking that I'm not going mad, since it's been a while since I did anything approaching real maths, or I've done something wrong somewhere and I'm just getting the wrong answer...
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Old 04-29-2015, 08:46 PM   #9872
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Not correct in fact. This is 4(e^-0.2t), not (4e)^-0.2t
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Old 04-29-2015, 08:47 PM   #9873
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^
that too, watch out for that

if you've got a scientific calculator then you can actually check it, just replace "t" with whatever value you want

but yeah, anything to the power of 0 = 1, anything to the power of 1 is itself. So in this case, -0.2 * 0 = 0. which makes e ^ 0 = 1
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Old 04-29-2015, 08:49 PM   #9874
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Quote:
Originally Posted by sickman411
Not correct in fact. This is 4(e^-0.2t), not (4e)^-0.2t

Ahhh, I thought if I was going to get something wrong it would be that, I'm generally a programmer so knowing how tight the operators bind isn't something I generally have to worry about!

So by that it comes out to 4, right? Again, just for sanity checking as much as anything else!
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Old 04-29-2015, 08:51 PM   #9875
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4 * 1 does = 4 yes

also, for whoever cares, i passed that maths exam i was worried about, got a C which isn't bad. I panicked on the day and made a load of stupid mistakes, but meh, I passed which is the main thing
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Old 04-30-2015, 01:16 AM   #9876
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Quote:
Originally Posted by Bladez22
4 * 1 does = 4 yes

Got to make sure, haha, abstract variables and stuff I can do... basic arithmetic and algebra? Not my strong suit!
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