The rectangles in the graph below illustrate a left endpoint Riemann sum for f(x) = -x^2/6 + 2x on the interval [4, 8]. The value of this left endpoint Riemann sum is, and it is an the area of the region enclosed by y = f(x), the x-axis, and the vertical lines x = 4 and x = 8.
Left endpoint Riemann sum for y = -x^2/6 + 2x on [4, 8]
The rectangles in the graph below illustrate a right endpoint Riemann sum for f(x) = -x^2/6 + 2x on the interval [4, 8]. The value of this right endpoint Riemann sum is, and it is an the area of the region.