# Homework Help: Volume of revolution, where am i going wrong?

1. Jul 7, 2013

### helpmeplz!

1. The problem statement, all variables and given/known data
Find the volume of solid obtained by rotating the region bounded by y=x^2,y=4 and x=0 about the line x=-2 using the shell method.

2. Relevant equations
I'm stuck because using disks I got the right answer 136pi/3 but I cant using shells?

3. The attempt at a solution
Integral 2pi (2+x) (4-x^2) dx from x=0 to 2. This gives 88 pi/3..

2. Jul 7, 2013

### LCKurtz

Why do you think $136\pi/3$ is correct? Your $88\pi/3$ looks correct to me. Hard to say what mistake you make, not seeing your work.

3. Jul 7, 2013

### jjpp109309

I agree, the correct answer is 88/3 *pi

4. Jul 7, 2013

5. Jul 7, 2013

### Redbelly98

Staff Emeritus