4. (1 Point) Quick Multiple Choice (a) True or False: There is a function f of two variables with Vf(,y) = 3. 0 True Q False (b) True or False: There is a function g of two variables with ||V9(P)|| = 5 and Duh(P) = 10 for some point P and some unit vector 11. 0 True 0 False (c) True or False: If Vh(P) = (1, 5) and v = (1,1), then Duh(P) = 6. 0 True 0 False (d) You are standing on a point where the temperature gradient points in the northwest direction. Which one of the following directions should you move in to experience no change in temperature? 0 North 0 N orthwot 0 Southwest 0 Southeast 5. Consider the surface mzerl y223 = 0. (a) (1 Point) Find an equation for the tangent plane to the surface mug1 3,323 = O at the point (1,1, 1). (b) (1 Point) Use part (a) to approximate 2 when m = 1.1 and y = 0.8