Draw it out.

You will find the intersection of the two parabola is at and that the area bounded on either side of are mirror images of each other.

Use disc integration, where

But since the region in is a mirror of the one at , you can simply integrate over the second region and multiply the volume by two:

Essentially, what you are doing is taking the volume of a cylinder whose radius varies. In this case, the radius is dependent on the parabola that you are integrating under (do you see it from your drawing)?