Question

How do you write the formula for the nth term given 8, -16, 32, -64,...?

Answer 1

`(-1)^(n-1) 2^(n+2)`

Explanation:

It is a geometric series, with first term 8 and common ratio -2, hence the nth term would be `ar^(n-1)`

= `8(-2)^(n-1)`

= `(-1)^(n-1) (8) 2^(n-1)`. This can also be written as `(-1)^(n-1) 2^(n+2)`