For the function f(x,y)=x3+y3−3xyf(x, y) = x^3 + y^3 - 3xyf(x,y)=x3+y3−3xy, find all critical points.
(0,0)(0, 0)(0,0) and (1,1)(1, 1)(1,1)
(0,0)(0, 0)(0,0) and (1,−1)(1, -1)(1,−1)
(1,1)(1, 1)(1,1) only
None