試題詳解

1. Find all critical points for the function f(x, y) = x³ - y³ + 33xy and classify each as a relative maximum, a relative minimum, or a saddle point.
(A) fhas a saddle point at (11,-11) and a relative minimum at (0,0).
(B) fhas a saddle point at (0,0) and a relative maximum at (11,-11).
(C) fhas a saddle point at (0,0) and a relative minimum at (11,-11).
(D) fhas a saddle point at (11,-11) and a relative maximum at (0,0).