I'm attempting to solve the following problem:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]\int_{0}^{\infty} {\frac{x arctan(x)}{(1+x^{2})^{2}}dx}[/tex]

I started with a substitution:

[tex]u=arctan(x), du=\frac{1}{(1+x^{2})}dx[/tex]

This seemed like the right thing to do, but after trying to put it together in several different ways I got nowhere. I looked at what WolframAlpha had to say. It got this after doing the same substitution:

[tex]\int_{}^{} {u sin(u)cos(u)du}[/tex]

I've gone at this for over half an hour now and I've gotten nowhere. Some insight into how this step was made would be appreciated.

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# Homework Help: Integration By Substitution

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