$\"\"$

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The series is $\"\"$ .

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$\"\"$ .

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The series is in the form of geometric series.

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The general form of geometric series is $\"\"$ .

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Compare the series with the general form.

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Here $\"\"$ and $\"\"$ .

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The series is converges if and only if $\"\"$ .

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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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Hence $\"\"$ .

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

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$\"\"$

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Hence $\"\"$ .

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Therefore, the series is convergence in the interval $\"\"$ . $\"\"$

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The series is convergence in the interval $\"\"$ .