# Math Help - Volumes

1. ## Volumes

Evaluate the volume generated by rotating about the y-axis the region bounded by the following curves: y=x^2,y=0,x=−2 and x=−1.

Quick question to clarify on this. Wouldn't I just find the volume of y=x^2 with the upper and lower bounds being -1 and -2 respectively?

2. Originally Posted by Hellreaver
Evaluate the volume generated by rotating about the y-axis the region bounded by the following curves: y=x^2,y=0,x=−2 and x=−1.

Quick question to clarify on this. Wouldn't I just find the volume of y=x^2 with the upper and lower bounds being -1 and -2 respectively?
you need to use cylindrical shells. the volume is: $\int_{-2}^{-1}-2\pi x^3 \ dx=\frac{15 \pi}{2}.$

3. How did you get x^3?