1. The problem statement, all variables and given/known data Integral Sqrt[16-x^2]*x dx from 0 to 2. 2. Relevant equations 3. The attempt at a solution First thing I do is a u-sub, so u=16-x^2 du=-2xdx I also my bounds change to upper=12 lower=16. After I integrate and swap out my U, I get -1/3*(16-x^2)^(3/2) from 16 to 12. Am I using the wrong method?