1. The problem statement, all variables and given/known data Hey all. I'm having issues with a few Diff. Eq. problems. I think I'm screwing up at the point of u-substitution, but I do not know for sure. 2. Relevant equations I'm evaluating: (x2 + x3)*integral (x4/(x4+2x5+x6) 3. The attempt at a solution I eliminate x4 inside the integral and evaluate: x*(x+1)*integral(dx/(x+1)2) = x2*(x+1)/-(x+1). Cancel out (x+1), and my answer is = -x2. However, the back of the book says the answer should be x2 (positive). Can anyone point out as to what I'm doing wrong? I've gotten a few of these wrong, usually because they are in the denominator and I do u-substitution. P.S.: If anyone has a link on how to use Latex Reference, it'd be greatly appreciated. I tried a few things and could not get it to work, for the life of me. Latex text: [tex]y_2[/tex] Many thanks.