$\"\"$

The series is $\"\"$ , and $\"\"$ .

Find the missing property sequence.

$\"\"$ and $\"\"$

The common ratio is

$\"\"$

The general formula of $\"\"$ -term sum of a geometric series $\"\"$ .

Find $\"\"$ .

Substitute $\"\"$ , $\"\"$ and $\"\"$ .

$\"\"$

The value of $\"\"$ is $\"\"$ .

$\"\"$

The value of $\"\"$ is $\"\"$ .