In Figure 1 you will find a contour map of a function f(x, y). The positive x direction is to the right, and the positive y direction is up. (a). Is fx (100, 100) positive or negative? Justify your answer. (b). Is fy(50, 100) positive or negative? Justify your answer. 150 125 100 75 50 50 25 0 25 -25 4000- 4500- 4000- 8000 10000 6500 6000- 6500- 5500- 7000 5000 4500- 7500- 8000- 9000 8500 9500- 10500 11500- 11000 -10000 7500- 8500 9000 5500- 6000 5000 6000 5000 3500 11500 11000 10500 10000 9500 9000 8500 8000 8000 7500 7000 6500 6000 5500 5000 4500 4000 3500 6500 7000 4500~ 4000 -3500- 3500- 3000- -50 -50 -25 0 25 50 75 100 125 150 FIGURE 1. Contour map of from question 7 = (0,0) in the (c). Is the directional derivative of f at the point where (x, y) direction of the vector < 1,1> positive or negative? Justify your answer. 3000