# U-sub for a specific integral

1. Aug 12, 2003

### suffian

i've been trying to get the following u-substitution to work for this integral for a while now, but i just cant get it.

&int; ( (x2-1)(x+1) )-2/3 dx

u = tan-1x (inverse tangent)

can anyone help me out here?

it's a textbook problem; and, the sub must work since the book cites the source of the problem as a math journal and list several other subs that should work as well (a couple of which i could get - the answer is (3/2)(x-1)1/3 / (x+1)1/3 + C).

edit: forgot +C

Last edited by a moderator: Aug 12, 2003