Problem:
Using both right-hand and left-hand endpoints, find the Riemann sums for the function
with n subintervals and simplify.

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Solution:

1. We first define Dx.

2. We now define a_i, i = 0, 1, 2, ..., n, the endpoints of these subintervals.

3. We evaluate f(a_i)

4. We form the Riemann sum using left-hand endpoints:

5. Simplifying, we obtain

6. We form the Riemann sum using right-hand endpoints:

7. Simplifying, we obtain