Calculate a Riemann sum S3,3 on the square R = [0, 3] x [0, 3] for the function g(x, y) = f(x, y) - 7. The contour plot of f(x, y) is shown in Figure 4. Choose sample points and use the plot to find the values of f(x, y) at these points. Use the values of f(x, y) to evaluate g(x, y) accordingly. 13 1 32 P12 P22 4 P31 X 0 FIGURE 4 Contour plot of f(I, y). S3.3