Question

A recursive rule for an arithmetic sequence is a1=-2; an=an-1 -9

What is an explicit rule for this sequence?

Answer 1

`a_n = -9n +7 \,,\,\,\,n\geq1`

Explanation:

This is an arithmetic sequence with a common difference of -9. We use this fact to create an explicit rule:

`a_n = -2 - 9(n-1)= -2 -9n +9 = -9n +7 \,,\,\,\,n\geq1`