1. The problem statement, all variables and given/known data Hi, the next problem I thought it was easy...and I really think it is, but I haven't come with the right answer :S. I compare the answer in an internet page of problems and all it says is "wrong"... The problem is the following: Find the volume of the solid obtained by rotating the region bounded by y=8*x+32, y=0 about the y-axis. 2. Relevant equations I made the sketh in Maple: http://img109.imageshack.us/img109/5669/solidvolumexi5.th.jpg [Broken] 3. The attempt at a solution Then I solve for x: x=(y/8)-4 and wrote the Integral with respect to y, and limits from 0 to 32 (where the function y=8x+32 intersects the y-axis). Integral of Pi*f(x)^2, from y=0 to y=32, it should give me the volume, isn't it? http://img164.imageshack.us/img164/98/equationie6.th.jpg [Broken] My answer: 512/3 * Pi= 536.1651462 But the internet page says I'm wrong but I don't know why :S Any help is welcome, Thanks in advance!