Question

9,-81, 729,-6561...
What is the common ratio?
Help which is the correct answer?

Answer 1

`r = -9`

Explanation:

Given

`Sequence: 9,-81, 729,-6561...`

Required

Determine the common ratio

The common ratio r is calculated using:

`r = (T_n)/(T_(n-1))`

Let
`n = 2`

So, we have:

`r = (T_2)/(T_(2-1))`

`r = (T_2)/(T_1)`

From the sequence:

`T_2 = -81`

`T_1=9`

So, the equation becomes

`r = (-81)/(9)`

`r = -9`