$\"\"$

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The sum of a geometric series is $\"\"$ .

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Where $\"\"$ is first term and r is common ratio.

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ ) $\"\"$

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$\"\"$ (Evaluate powers: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ )

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$\"\"$ (Multiply: $\"\"$ )

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$\"\"$ (Divide: $\"\"$ ) $\"\"$

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The value of $\"\"$ .