$\"\"$

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The series is $\"\"$ .

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Rewrite the series as $\"\"$ $\"\"$ .

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Maclaurin series of function $\"\"$ , $\"\"$ .

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Compare the series with $\"\"$ .

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Here $\"\"$ .

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Therefore, $\"\"$ .

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$\"\"$ .

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$\"\"$

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The sum of series $\"\"$ .