1. The problem statement, all variables and given/known data Find the local max/min or saddle points of f(x,y) = (x-y)(1-xy) 2. Relevant equations 3. The attempt at a solution I expanded the equation to f(x,y) = x-y-(x^2)y+xy^2. Then I found the partial derivatives of the function. fx = 1-2xy +y^2 fy = -x^2-2xy I'm stuck after this part. Usually I can set the function to 0 and solve for x or y, but I can't do that here.