Follow the directions of Problem 33 for
z = x - x3/9 - y2
Plot the graph of
z = x2 - y2
on -5 ( x ( 5, -5 ( y ( 5; also plot its contour map and gradient field, thus illustrating Theorems B and C. Then estimate the xy-coordinates of the point where a raindrop landing above the point (-5, -0.1) will leave this surface.