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    Hey,

    How would I integrate x^2*tan^-1x?? I'm stuck on what to do with the x^2 bit. I know that tan^-1x gives 1/(1+x^2). Thanks.
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    Are you integrating or differentiating? I'm guessing you mean differentiating because you can't integrate that function.

    Use the product rule, letting x^2=u and tan^-1x=v. You know dv/dx because you just posted it, and du/dx is just 2x.

    Then your answer will be:
    u(dv/dx) + v(du/dx) = x^2(1/(1+x^2)) + (tan^-1x)2x

    and you can re-order the terms a bit to make this look nicer.
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    If you are integrating, why not just use integration by parts?
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    (Original post by ttoby)
    Are you integrating or differentiating? I'm guessing you mean differentiating because you can't integrate that function.
    http://www.wolframalpha.com/input/?i...ate+x^2arctanx
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    +1

    Thought I'd gone crazy for a second, was about to consult Wolfram myself!
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    Can anyone help me, I haven't got a clue what to do.
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    (Original post by FutureMedic)
    Can anyone help me, I haven't got a clue what to do.
    Are you 100% certain that \int x^2 \arctan x\ dx is what you're trying to work out? Integration by parts is the way to do it but the integral of \arctan x definitely wasn't on my C3 syllabus...
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    Good point. I'm sure I typed it into Wolfram Alpha myself but I must have typed it wrong. +rep
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    (Original post by chigley)
    Are you 100% certain that \int x^2 \arctan x\ dx is what you're trying to work out? Integration by parts is the way to do it but the integral of \arctan x definitely wasn't on my C3 syllabus...
    Oh, not integrate... differentiate. :P Sorry.
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    (Original post by FutureMedic)
    Oh, not integrate... differentiate. :P Sorry.
    Just use product rule
    if equation is in the form
    y=uv
    dy/dx=u'v+uv'
 
 
 
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