Question

Write a recursive formula for the following arithmetic sequence.

-6, -9, -12, -15, ...

Answer 1

`a_(n)` =
`a_(n-1)` - 3

Explanation:

The recursive formula lets us find a term in the sequence by adding the common difference d to the previous term.

Here d = a₂ - a₁ = - 9 - (- 6) = - 9 + 6 = - 3 , thus

`a_(n)` =
`a_(n-1)` - 3 with a₁ = - 6