Consider the function (x, y) = x 2 (y + 1) 2 + k(x + 1) 2 y 2 . (a) For what values of

Consider the function ƒ(x, y) = x²(y + 1)² + k(x + 1)²y².

(a) For what values of k is the point (x, y) = (0, 0) a critical point?
(b) For what values of k is the point (x, y) = (0, 0) a relative minimum of the function?