Is 3, 6, 9, 12 ,15, 18 a geometric sequence?

1 Answer
Dec 16, 2015

Answer:

No, it's an arithmetic sequence with initial term #3# and common difference #3#.

Explanation:

A geometric sequence has a common ratio between terms.

An arithmetic sequence has a common difference between terms.

If a sequence of Real numbers is both a geometric sequence and an arithmetic sequence then it is constant.

Note I say Real numbers. The sequence #1, -1,1,-1,...# is both an arithmetic and geometric sequence in modulo #4# arithmetic, with common difference #2# and common ratio #-1#.