An arithmetic sequence is a sequence of numbers that increases or decreases by a constant amount each term. a n = dn + c, where d is the common difference.
We have then:
3, 6, 9, 12, 15
It is an arithmetic sequence.
Their common difference is:
dn = an - c = 6 - 3 = 3
Answer:
3, 6, 9, 12, 15