Question

How do you find the common ratio, r, for the geometric sequence that has a1 =100 and a8 = ?

Answer 1

`r=root(7)(a_8/a_1)`

See explanation.

Explanation:

The task is incomplete, because the term `a_8` is missing, but it is possible to show the way to solve the task.

According to the `n-th` term formula we can write, that:

`a_8=a_1*r^7`, so

`r^7=a_8/a_1`

`r=root(7)(a_8/a_1)`