Problem 8: (5 Points) By about how much will g(x, y,z) = x + x cosz - y sinz + y change if he point P(x, y, z) moves from Po (2, -1,0) a distance of ds = 0.2 unit toward the point P, (0,1,2)? (Ans: 0, no change) Problem 9: (10 points) Find all the local maxima, local minima, and saddle points of the following function. f (x, y) = 4xy - x4 - y+