Homework: Ch 7 Part1 Score: 0 of 1 pt 7.3.7 80f 10 (6 complete) â¼ Approximate the area under the graph of f(x) and above the x-axis with rectangles, using the following methods with n 4. f(x)--x2 + 7 from xs-2tox#2 (a) Use left endpoints. (b) Use right endpoints. (c) Average the answers in parts (a) and (b) (d) Use midpoints. (a) The area, approximated using the left endpoints, is