can some please explain this to me:

if dv = cos 5x dx, how does v = 1/5 sin 5x ??

--i get something totally different (5/2 x^2 sin 5x )

Thanks for any help!

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- April 7th 2007, 04:17 PMadam21Trying to integrate cos 5x
can some please explain this to me:

if dv = cos 5x dx, how does v = 1/5 sin 5x ??

--i get something totally different (5/2 x^2 sin 5x )

Thanks for any help! - April 7th 2007, 04:34 PMJhevon
- April 7th 2007, 04:38 PMJhevon
You can check your answers by differentiating the answer you got when you integrate.

If you differentiate 5/2 x^2 sin 5x you don't get cos(5x), but if you differentiate (1/5)sin(5x) you do.

i'm not sure where you made your mistake, but i think you were mixing up the product rule somewhere in all this, but you don't have a product - April 7th 2007, 04:38 PMtopsquark