Approximate the area of the region bounded by y equals short dash 1 half x squared plus 10, the x-axis, x equals 0, and x equals 4 by finding the combined area of the rectangles (as shown in each figure) and averaging the results. 20 space u n i t s squared b.) 8 space u n i t s squared c.) 28 space u n i t s squared d.) 14 space u n i t s squared