$\"\"$

If $\"\"$ , $\"\"$ and $\"\"$ .

Find the missing property sequence.

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

Find $\"\"$ .

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

$\"\"$

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

$\"\"$

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