∫xdx/(x^2-x-2)
=∫xdx/[(x+1)(x-2)]
= (1/3)∫[2/(x-2)+1/(x+1)]dx
= (2/3)ln|x-2| +(1/3)ln|x+1| +C
= (1/3)ln|(x+1)(x-2)^2| +C