In the graph, f(1) = 6, f(2) = 4, f(3) = 3, f(4) = l. 1, 1 ( }) Jr=f(x) (2.112)) (3,113)) (a) Approximate the shaded area under the graph of f by constructing rectangles using the left endpoint of each subinterval. (Use symbolic notation and fractions where needed.) (b) Approximate the shaded area under the graph of f by constructing rectangles using the right endpoint of each subinterval. (Use symbolic notation and fractions where needed.) Arm = E