1. The problem statement, all variables and given/known data Find and classify the extrema of f = x3 - 3xy2 + y3 3. The attempt at a solution I find partial deriv. with respect to x is 3x2 - 3y2 and the partial deriv. with respect to y is -6xy + 3y2 I set these to zero, and for my critical point I get (0,0). This can't be right... where am I going wrong?