A geometric sequence can be identified because each term can be found as the product of the previous term and a fixed number r, called the common ratio.
We are given the sequence:
3,6,12,24,...
If we are able to find a constant common ratio, then this is a geometric sequence.
Dividing the second by the first term:
r = 6/3 = 2
Dividing the third by the second term:
r = 12/6 = 2
Dividing the fourth by the third term:
r = 24/12 = 2
Note we have calculated the common ratio and we have gotten the very same value in all the cases, thus:
It's True