1. The problem statement, all variables and given/known data Revolve the region under the curve y =√x on the interval [0, 4] about the x-axis and find the volume of the resulting solid of revolution. YET, NOW, I want to do in respect to y 2. Relevant equations integral formula 3. The attempt at a solution I did dx and I got 8pi which is corrected. So I decided to do it with dy. I looked at the graph and I saw the height would be the same (well because of the problem's nature). so a and b will stay the same integral of pi*r^2 we know r is y^2 (since y^2 = x) integral of pi * (y^2)^2 from 1 to 4 but I did not get 8pi why? thanks.