Answer:
Neither
Step-by-step explanation:
If the sequence is arithmetic, there will be a common difference.
6 − (-3) = 9
-9 − 6 = -15
12 − (-9) = 21
The sequence is not arithmetic.
If the sequence is geometric, there will be a common ratio.
6 / -3 = -2
-9 / 6 = -3/2
12 / -9 = -4/3
The sequence is not geometric.