Answer:
So, the common difference (d) for this arithmetic sequence is -6.
Explanation:
In an arithmetic sequence, the common difference (d) is the constant value by which each term is obtained by adding or subtracting. To find the common difference for the given sequence, let's calculate it:
1st term: 21
2nd term: 15
3rd term: 9
4th term: 3
5th term: -3
To find the common difference, you can subtract any term from the previous term. Let's use the first two terms:
Common difference (d) = 15 - 21 = -6
So, the common difference (d) for this arithmetic sequence is -6.