$\"\"$

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The function is $\"\"$ and the equations are $\"\"$ , $\"\"$ .

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$\"\"$ , where $\"\"$ is the right endpoint of the partition.

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$\"\"$ .

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$\"\"$ is the width of the $\"\"$ interval.

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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Apply summation formula $\"\"$ .

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Apply summation formula $\"\"$ .

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$\"\"$

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As $\"\"$ , then $\"\"$ .

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$\"\"$

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$\"\"$ .

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$\"\"$

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$\"\"$ .