WEBVTT

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Here is the problem: sum of 2n plus 1 from n equals 0 to 9.

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Add the terms 2~ n plus 1 for n equals 0, 1, …, 9 (10 terms).

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Write the sum.

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List the first terms.

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Add all 10 terms exactly (as fractions).

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So the answer is 100.

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Each term is computed exactly and added. For long arithmetic or geometric sums a closed formula gives the same result.

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Decimal value: 100.