The integral of 2x/(1+x^4).

I don't have an integral sign on this thing... so I just need that integrated.  Any substitution that I could make that would work?  And a brief explanation would be great :).

Erm I can't see a substitution you can do. If you find one, let me know.

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I came on Eileen
2(✈) + 2( ▌) = -3017

Intelligence:Confusing Americans since MDCCLXXVI

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bleurgh! I'm meant to be dong some maths right now.

Erm I can't see a substitution you can do. If you find one, let me know.

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It was on a quiz I had, and I would have assumed there would have been a substitution problem in it...

I'm pretty sure the answer is arctan (x^2), and that would give you the right answer.... OH.  Duh... That's the substitution!  Haha.

u = x^2.

Therefore, you have...

2x/(1+u^2)*dx.

du = 2xdx.

Therefore you have...

the integral of 1/(1+u^2)*du

1/(1+u^2) is arctan (u).

Then, substituting u=x^2, you get arctan (x^2).

Haha, alright, I got it ^__^.

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^ he got it. Don't forget the +C at the end. XD

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Oh... I think I did forget it on the quiz -__-'. I always forget it, unless we're integrating twice, because then I know I ~have~ to have it...

Yup... got it back today.  I lost a mark for it.

Post edited at 8:34 pm on Dec. 2, 2008 by Just Waiting Here