Question

Is the sequence 5, 9, 15, ... an arithmetic sequence? Explain. Type your answer below.

Answer 1

Nope an arithmetic sequence increases monotonously with d.
First item lets say a. Second a+d, third a+d+d and so on
5,9,15
9-5=4 thus if it is an arithmetic sequence d=4
9+4=13 not 15.
So answer is NO

Answer 2

I agree....arithmetic sequences are done by adding. The difference between the numbers must be the same.