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Math Help - need help integrating x^2cos(x^2)dx

  1. #1
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    need 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
    Last edited by ihaveamathproblem; March 26th 2008 at 12:13 PM. Reason: wrong problem
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  2. #2
    Eater of Worlds
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    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.

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

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

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

    =sin(x^{2})
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