## Algebra 1: Common Core (15th Edition)

You have the sequence 1.5,4.5,13.5,40.5. You have to determine if it is an arithmetic or geometric sequence: Arithmetic you have to find the common difference: 4.5-1.5=3 40.5-13.5=27 There is no common difference so this is not arithmetic. Geometric you have to find the common ratio: r=$\frac{4.5}{1.5}$=3 r=$\frac{40.5}{13.5}$=3 There is a common ratio 3. So the sequence is geometric.