What is the common ratio in this geometric sequence 3, 18, 108, 648, 3888, ...?

1 Answer
Nov 9, 2015

Answer:

The ratio is #6#.

Explanation:

A term in a geometric series are obtained by multiplying the previous one by a fixed value, called ratio, which we will call #r#.

So, the second term #18# is obtained by the first, #3#, multiplying by a value which we can easily find: if #18=3*r#, then #r=18/3=6#.

The same goes for the third, since #108=18*6#, and so on.

You can check that also the reimaining terms obey this rule, so the ratio is #6#.