Antiderivative of x^3 (x^2 + 1)^3/2 using substitution

[flyguy03]

I am having problems with the following integrand

{x^3 (x^2 + 1)^3/2 dx

let u = x^2 + 1 du = 2x dx 1/2 x^2 = du x^3 dx

This is where i get lost. I do not know how this fits in to the integrand. I thought that in order to bring the term in front of du out of the integrand it needed to be a constant.

ie 1/2 x^2 { u^3/2 du

Thanks in advance[/list]

 

[skeeter]

I knew I already did this exact same problem once before ...

http://www.freemathhelp.com/forum/viewtopic.php?t=19339

 

[flyguy03]

Thank you very much