Tell whether the sequence is arithmetic. If it is, what is the common difference?
–15, –9, –3, 3, . . .
A. Yes; 3
B. Yes; 5
C. Yes; 6
D. No
The given sequence is not arithmetic because the common difference between consecutive terms is not the same. The difference between -15 and -9 is 6, but the difference between -9 and -3 is 6 as well. However, the difference between -3 and 3 is 6. Since the common difference is not constant, the sequence is not arithmetic.
Therefore, the answer is D. No.