
Suppose .
(a) The rectangles in the graph on the left illustrate a left endpoint Riemann sum for on the interval . The value of this left endpoint Riemann sum is , and it is an
the area of the region enclosed by , the xaxis, and the vertical lines and .
(b) The rectangles in the graph on the right illustrate a right endpoint Riemann sum for on the interval . The value of this right endpoint Riemann sum is , and it is an
the area of the region enclosed by , the xaxis, and the vertical lines and .
 




Left endpoint Riemann sum 

Right endpoint Riemann sum 
