Then improve your estimate by using six rectangles R6 1 Sketch the curve and the approximating rectangles for R3 a Estimate the area under the graph of f x 3 4x from x 1 to x 2 using three rectangles and right endpoints R3 15 y 10 M 5 15 II 10 e 2 X 0 1 15 10 5 15 10 y y Ih S 1 2 x