Question

Which answer describes the type of sequence? 3, 9, 15, 21, ...

geometric

arithmetic

neither arithmetic nor geometric

Answer 1

I am not 100% sure, but I think that it is arithmetic

Answer 2

The sequence is arithmetic

Explanation:

we know that

In an arithmetic sequence, the difference between consecutive terms is always the same and is called common difference

In this problem we have

`3,9,15,21,...`

Let

`a1=3, a2=9,a3=15,a4=21`

`a4-a3=21-15=6`

`a3-a2=15-9=6`

`a2-a1=9-3=6`

The sequence is arithmetic

The common difference is equal to
`6`