I know how to use the shell method for this problem. But I'm not sure how to solve it using disk or washer. I know you solve for X which gives you X=(Y)^(.25).

The parameters are. Y=x^4 x=0 y=81

I know is the equation for washer method.

This mean . Now I'm lost? What's the Big R and Little r now.

Big R= 81-0?

Little r= (Y^(.25))-0?