# What is the 7th term of the geometric sequence 3, 9, 27,...?

##### 1 Answer

Oct 6, 2014

A geometric sequence has a constant ratio (common ratio) between consecutive terms.

For 3, 9, 27, ... the common ratio is 3 because:

3 X 3 = 9

9 X 3 = 27

So to find the 7th term you can do it two ways:

**One way:**

3 is the 1st term, 9 is the 2nd term, 27 is the 3rd term so then

4th term: 27 X 3 = 81

5th term: 81 X 3 = 243

6th term: 243 X 3 = 729

7th term: 729 X 3 = 2,187

**Another way:**

You can use the explicit formula

so

Both ways get you to the same answer that the 7th term in that geometric sequence is 2, 187 .