Question

Is "12, 15, 18, 21..." an arithmetic sequence?

Answer 1

Yes.

Explanation:

A sequence is arithmetic if each term shares a common difference with the preceding term, `d,` IE, `a_2-a_1=d, a_3-a_2=d,...,a_n-a_(n-1)=d`

Here, `15-12=3, 18-15=3, 21-18=3,` so the common difference is `3` and this is in fact an arithmetic sequence.