Patrick B. answered 07/21/19
Math and computer tutor/teacher
Approximation is
(-1.5 - -3)*4 + (1.5 - -1.5)*8.5 + (3 - 1.5)*4 =
1.5*4 + 3*8.5 + 1.5*4 =
6 + 28 + 6 = 40
The integral is 9x - (1/3)x^3
x=3: 9*3 - (1/3)*3^3 = 27 - 9 = 18
x=-3: 9*-3 - (1/3)*(-3)^3 = -27 - (-9) = -18
The exact area is 18 - -18 = 36
