# Homework Help: Volume Shell Method

1. Feb 1, 2013

### whatlifeforme

1. The problem statement, all variables and given/known data
use the shell method to find the volumes of the solids generated by revolving the region about the indicated axis.

2. Relevant equations
x=18(y^2 - y^3) about line y=8/5.

3. The attempt at a solution
2∏∫ (0 to 1) (8/5 - y) (18y^2 - 18y^3)

2. Feb 1, 2013

### HallsofIvy

This single equation does not define a bounded region. Was there some other line or curve given, such as the y-axis (x= 0)?

3. Feb 1, 2013

### whatlifeforme

according to the graph it appears bounded by y-axis. (x=0)

4. Feb 1, 2013

### Staff: Mentor

Assuming that the region to be revolved is between one arch of the curve and the y-axis, your setup looks fine, except that you are missing the differential. It might not seem important now, but when you learn more techniques of integration, omitting the differential will be a big problem.

What do you get for the value of your integral?