Step 1:

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The function is $\"\"$ , interval is $\"\"$ .

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Number of rectangles is $\"\"$ .

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The sum of all inscribed rectangle is Lower sum.

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$\"\"$

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where $\"\"$

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The sum of all circumscribed rectangle is Upper sum.

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$\"\"$ .

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where $\"\"$

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Where $\"\"$ .

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Step 2:

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Lower Sum:

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$\"\"$

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Area of lower sum is $\"\"$

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$\"\"$

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Sum of square of natural numbers is $\"\"$ .

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$\"\"$

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Step 3:

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Upper Sum:

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$\"\"$

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Area of higher sum is $\"\"$

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$\"\"$

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Sum of square of $\"\"$ natural numbers is $\"\"$ .

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$\"\"$

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Then $\"\"$

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$\"\"$

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$\"\"$

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Solution :

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$\"\"$