A recursive rule for an arithmetic sequence is a1=-2; an=an-1 -9 What is an explicit rule for this sequence?

Question

asked Aug 21, 2019 110k views

1 Answer

Erdekhayser · Answer 1 · 2019-08-26T22:34:30+0000

Answer:

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

Explanation:

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

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