Estimate the area under the graph of f (a?) : 9 $2 over the interval [1, 2] using eight approximating rectangles. Round your answers to two decimal places. a. Using right endpoints, we get R3 : b. Using left endpoints, we get L3 : c. For an even better estimate, we can find the mean (average) of R" and Ln. Find the average of these two values. RglLg 2