`1, 1/2, 1/3, 1/4...` Determine whether the sequence is geometric. If so, find the common ratio.

You need to verify if the sequence is a geometric sequence, hence, you need to use the following property, such that:

`a_n = sqrt(a_(n-1)*a_(n+1))`

Replacing `1/2` for `a_n, 1` for `a_(n-1)` and `1/3` for `a_(n+1) ` yields:

`1/2 = sqrt(1*1/3) => 1/2 != 1/sqrt3`

Since the given sequence is not geometric, the ratio cannot be found.