Question

How do you find the explicit formula for the following arithmetic sequence 123, 116, 109, 102, 95, ...?

Answer 1

`a_n= 123-7(n-1)`

Explanation:

When defined explicitly:
`a_n= a_1+d(n-1)`

`a_n` is the nth term
`a_1` is the first term
`d` is the difference

The difference is:
`116-123= -7`

So this can be written as:
`a_n= 123-7(n-1)`