Question

#10 Please help me :)

Answer 1

The third choice is the one you want.

Explanation:

The formula for an arithmetic sequence is as follows:

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

Our first number is 8, so a1 = 8. If the second term is 5, then d = -3. Filling in our formula gives us this:

`a_(n)=8-3(n-1)`

Now we need domain. Our choices are n ≥ 1 and n ≥ 0 so let's try both. Replace n in the formula with each one, one at a time, and see what the result is.

If n ≥ 0:

`a_(0)=8-3(0-1)` so
`a_(0)=8-(-3)` which gives you that the first term, defined by
`a_(0)` is 11. That's not correct. Let's check n ≥ 1
`a_(1)=8-3(1-1)`

and
`a_(1)=8-0` which is 8, the first term.