Hi, I am doing my homework, but the book does not have any solutions so I can not verify my results. i wouldn't be a problem if I were 100% sure that I'm doing it right, but since I had some problems calculateing the limits of integration I'll ask you folks to help me! SO here is my first problem: SSdxdy over DELTA. DELTA is characterised by these four equations: x*y=1; x*y=4; y=x; y=2x. I think that the integral should look like this S sqrt(2)/2 -> 2 ( S x -> 2x dy) dx . Am I right?