For finding the sum of terms in a finite geometric series, we use the following formula where = the first term in the series and = the common ratio

(1)

(2)

**Example 1:**

Find the sum of the first 6 terms of the geometric series 2 + 4 + 8 + …

We’ll use the first equation knowing that , , and

(3)

**Example 2:**

Find the sum of the first n terms of the geometric series given , , and

(4)