Question

Which sequences are geometric? Check all that apply.

10, 7.5, 5.625, 4.21875, …
160, 40, 10, 2.5, …
20, 70, 245, 857.5, …
13, 16.5, 20, 23.5, …
5, 5.5, 6.05, 6.655, …
16, 17.1, 18.2, 19.3, …

Answer 1

geometric series: each subsequent term is made by taking the previous term and multiplying by r

so to find the geometric series: go through each item in a series, divide by the previous term. repeat for all terms. if **all* terms in the series result in the same ratio, then its geometric.