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Math Help - Integration by parts -- check my answers plz

  1. #1
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    Integration by parts -- check my answers plz

    I had to use integration by parts..Anyone mind checking my answers :P

    1) int from 0 to pi/4 xsin(2x) dx = 1/4
    2) int from 0 to 1 arctanx dx = 0.4388

    3) int sin(lnx) dx = sin(lnx)e^(lnx) - cos(lnx)e^(lnx) / (1-e^(lnx))
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  2. #2
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    Quote Originally Posted by Beeorz View Post
    I had to use integration by parts..Anyone mind checking my answers :P

    1) int from 0 to pi/4 xsin(2x) dx = 1/4 Mr F says: Correct.
    2) int from 0 to 1 arctanx dx = 0.4388 Mr F says: Correct, to four decimal places.

    3) int sin(lnx) dx = sin(lnx)e^(lnx) - cos(lnx)e^(lnx) / (1-e^(lnx)) Mr F says: Note that e^(lnx) = x. The denominator is 2, no 1 - x.
    ..
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