I know how to do very basic and simple shell method problems, but this one is difficult for me. Every problem that I have had to do so far, the graphs always stay on one side of the x and y axis. Meaning they never cross it. This one does, however, and I don't understand how to work with that. So the information given is:

x= y^4/4 -y^2/2

x=y^2/2

There is a graph of this shown, and the graphs intersect at (0,0) and (2,2).

But the graph of y^4/4 - y^2/2 goes over to the left side of the y axis for a bit, and then goes back to the right. I need to find the volume of the region that would be formed by rotating the graph about the x axis. So how do I find the radius and the height for this? Maybe I'm making it more complicated than it is...