Do the following.
a = 20
(a) By reading values from the given graph of f, use five rectangles to find a lower estimate and an upper estimate for the area under the given graph of f from x = 0 to x = 40.
A 1 (lower estimate)
A 2 (upper estimate)
(b) Find new estimates using ten rectangles in each case.
A 3 (lower estimate)
A 4 (upper estimate)