Question

Find a lower and upper estimate of the area under the given graph of f from [0,10] by using five rectangles

Answer 1

"given graph of f"
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Answer 2

In other words, first use the right endpoints of the individual subintervals of [0,10] to estimate the area under f(x), and then the left endpoints. One will give you the upper estimate; the other the lower. The width of each subinterval is (b-a)/n, or (10-0)/5, or 2, in this particular problem.