Question

How do you tell whether the sequence `3, 5, 7, 9, 11,...` is geometric?

Answer 1

It is not geometric.
`a_n = 2n + 1`

Explanation:

Since in a geometric sequence each term after the first is found by multiplying the previous one by a fixed, non-zero number, thus we have to get that number by dividing nth term by the previous term.

We can say a sequence is geometric if and only if all of the division answers are fixed and constant.

`\frac{5}{3} \ne \frac{7}{5}` so your sequence is not geometric.