# How do you determine whether the sequence #3, 12, 21, 30,...# is geometric and if it is, what is the common ratio?

##### 1 Answer

Jul 17, 2017

It is not a geometric sequence and hence question of common ratio does not arise. It is actually arithmetic sequence and common difference is

#### Explanation:

A geometric sequence is one in which the ratio of each term to its preceding term is always constant. This ratio is called **common ratio**.

In the series,

we have

Hence it is not a geometric sequence.

However, we have **common difference** and hence it is an arithmetic sequence.