Need help solving simple integral

**downthesun01** · February 29th 2012, 03:06 AM

Wolfram Alpha gives an answer of $\frac{1}{2}$ , but it doesn't give the steps. Can someone walk me through the problem or a similar problem? I believe I need to use integration by parts but I keep getting stuck.

Thanks

$\int_{0}^{\infty}\frac{3x}{(1+x)^{4}}dx$

**skeeter** · February 29th 2012, 03:16 AM

Originally Posted by downthesun01

Wolfram Alpha gives an answer of $\frac{1}{2}$ , but it doesn't give the steps. Can someone walk me through the problem or a similar problem? I believe I need to use integration by parts but I keep getting stuck.

Thanks

$\int_{0}^{\infty}\frac{3x}{(1+x)^{4}}dx$

try the substitution $u = x+1$