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

1. ## 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))

2. Originally Posted by Beeorz
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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