4. [10 pts] The table below gives the values of a function f(x, y) on the square region R = [0, 4] x [0, 4]. The first row shows possible values of x, the first column possible values of y, and the rest of the table contains values of the function (for example, f (0, 2) = -2, f(1, 4) = -1, etc.). y x 0 1 2 3 4 O 2 3 5 2 - 2 2 4 4 -3 0 3 You have to approximate f(x, y) d.A using double Riemann sums. R (a) What is the smallest AA = AxAy you can use for a double Riemann sum given the table above? (b) Sketch R showing the subdivisions you found in part (a). (c) Assuming that of aJ. > 0, ay