Geometric sequence are sequence that has the same ratio. In determining if it is a geometric sequence is by dividing the second term (a2) to the first term (a1). 

Example would be:


If you divide 3 with 1 the answer would be three; if you divide 9 with 3 the answer would also be 3 and so on. Hope I was a help.

how about when im going to insert 3 geometric means between 16 and 81?
the 3 geometric numbers inside 3,16 and 81 would be: