# How do you find the explicit formula for a geometric sequence 9,19, 39,79,159,...?

##### 1 Answer

Mar 16, 2016

#### Explanation:

A geometric sequence is a sequence in which there is a common ratio between successive terms. The given sequence is not a geometric sequence, as, for example,

The sequence is close to a geometric sequence, however. If we add

The general term for a geometric series with common ratio

In that case, if the general term for the given series is

Subtracting