Hi, 1. The problem statement, all variables and given/known data I am asked to find the volume under the curve whose equation is z=16-(x^4+y^4), and within (x^2+y^2)<=1, using a double integral. 2. Relevant equations 3. The attempt at a solution Should I use cylindrical coordinates? I feel slightly lost. I have tried drawing z=16-(x^4+y^4), unsuccessfully. I understand that (x^2+y^2)<=1 is a circle of r<=1 and sets the limit to the volume, i.e. the base of the shape. I'd truly appreciate some guidance.