Question

PLEASE HELP!!!

what is the explicit formula for the sequence

7 2 -3 -8 -13

Answer 1

Assuming the index start from
`1`, i.e. the first element is
`a_1`, the answer is the last one:
`a_n = -5n+12`

In fact, the elements of the sequence differ by
`5` units from each other, and are descending, which justify the
`-5n` part.

Nevertheless, the sequence starts from
`7`, so when
`n=1` we must have

`-5+k=7 \iff k=12`

hence the formula

`a_n = -5n+12`

Answer 2

It is D.

When you plug in the step number instead of "n" you need to get "a" for your answer.