The function f(x) = -3x + 9 is defined on the interval [0, 3].
(a) Graph In (b)–(e), approximate the area A under from 0 to 3 as follows:
(b) Partition [0, 3] into three subintervals of equal length and choose u as the left endpoint of each subinterval.
(c) Partition [0, 3] into three subintervals of equal length and choose u as the right endpoint of each subinterval.
(d) Partition [0, 3] into six subintervals of equal length and choose u as the left endpoint of each subinterval.
(e) Partition [0, 3] into six subintervals of equal length and choose u as the right endpoint of each subinterval.
(f) What is the actual area A?