Approximate the area under the graph of 2 f(x) and above the x-axis with rectangles, f( X ) = - +3. from x = 1 to x = 9 using the following methods with n = 4 X (a) Use left endpoints (b) Use right endpoints (c) Average the answers in parts (a) and (b) (d) Use midpoints. The area, approximated using the left endpoints, is (Round to two decimal places as needed.)