. [6 points] Suppose that f(x,y) = 212 + ya (a) Find the gradient off at the point (2,1) (b) Find the directional derivative off at (2,1) in the direction of the vector V = (3,4). (6) 1What is the maximal rate of change of f at (2,1)? . [4 points] For the surface 2 = 282\" - 5x - 33:2 + 7, nd an eguation for the plane tangent to the surface at the point (0, 2, -3). 6w [6 points] Use the Chain Rule to find E in terms of x, y. z. s and t. w=32, x=4e'+23'25, y=253+3t', z=5tln{s) . [4points] Given that f(x, y) = sin (xy), Find the following partial derivative. [6 points] i. 15,; ii. fyy= Manuel Find fry in the given lnction in question #4