i know that i need to use integration by parts but i am stuck on picking my u and dv

EDIT: the problem is the integral of 2xcos(x^2)dx sorry

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- Mar 26th 2008, 12:11 PMihaveamathproblemneed help integrating x^2cos(x^2)dx
i know that i need to use integration by parts but i am stuck on picking my u and dv

EDIT: the problem is the integral of 2xcos(x^2)dx sorry - Mar 26th 2008, 12:28 PMgalactus
At first glance, I thought this was a Fresnel integral. Which is more difficult. But it is actually much easier than that.

Just use substitution instead of parts.

$\displaystyle 2\int{xcos(x^{2})}dx$

Let $\displaystyle u=x^{2}, \;\ du=2xdx$

$\displaystyle \int{cos(u)}du=sin(u)$

$\displaystyle =sin(x^{2})$