$\"\"$

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

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

Apply alternate geometric series sum formula $\"\"$ .

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

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

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

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

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

The value of $\"\"$ .