We are given the following series
-6, -2, 2, 6
Common difference = last term - first term
For the first two terms
The common difference is calculated as
Last term - first term
Last term = -2
First term = -6
Common difference = -2 - (-6)
= -2 + 6
common difference = 4
Common difference = 2 - (-2)
common difference = 2 + 2
Common difference = 4
Last two terms
common difference = 6 - 2
Common difference = 4
The common difference for this sequence is 4
The sequence is arithmetic.