Question

Which of the following choices is the simple formula for the nth term of the following arithmetic sequence?

5, 1, -3, -7, -11, ...

A. -4n + 9
B. 4n + 1
C. 4n + 9
D. 5n + 4
E. -4n + 1

Answer 1

First, we start off with the nth term formula for an arithmetic sequence, which is

`a_(n) =a_(1)+(n-1)d`

plug in the sequence numbers where they belong


`a_(n)=5+(n-1)*(-4)`

`a_(n)=5+(-4n+4)`

`a_(n)=5-4n+4`

`a_(n)=-4n+9`

And this is the final answer

`-4n+9`