We are computing a Riemann sum with {{MATH_6}} over the interval {{MATH_7}}. Therefore the subintervals are: {{MATH_8}} The midpoints of these subintervals are {{MATH_9}}, {{MATH_10}}, and {{MATH_11}}. The Riemann sum is: {{ENV_12}} {{COMMENT_13}} {{COMMENT_14}} {{COMMENT_15}} {{COMMENT_16}} {{COMMENT_17}} {{COMMENT_18}} {{COMMENT_19}} {{COMMENT_20}} {{COMMENT_21}} {{CMD_22}}