Suppose f (x,y) is a differentiable function. a) If (a,b) is a critical point of f (x, y) (in the sense that (a, b) = = 0, ' (a, b) = 0, will (a, b) be a critical point of g(x, y) = (f (x, y))?? b) If (a, b) is a critical point of g(x, y) = (f (x, y))?, in the sense that (a, b) = 0, ,(a, b) = 0, will (a, b) be a critical point of f (x, y)? hint: how are the partial derivatives of f (x, y) and g(x, y) related? Suppose that the level curves of a function z = f (x,y) consists of straight lines. Must the graph of f be a plane? Hint: check our class notes/recording when we discussed this topic!