Answer:
2
Explanation:
The common difference in an arithmetic sequence is the difference between any two terms
So, you could start by doing -3 + d = -1
-3 + d = -1
-3 + d +3 = -1 +3
d = 3 -1
d = 2
Now test it with other terms
-1 + d = 1
Substitute
-1 +2 = 1
2 -1 = 1
1 = 1
It works!!!
If you want you can try it with 1 and 3
1 + d = 3
1 + 2 = 3
3 = 3
I hope this helps!!!!