Answer
There is no common ratio, so this sequence is not geometric.
Work Step by Step
You have the sequence:5,10,15,20. Find the common ratio by using the formula: R=$\frac{a2}{a1}$,R=$\frac{a4}{a3}$.Plug in the values to get the ratios
r=$\frac{10}{5}$=2
r=$\frac{20}{15}$=$\frac{4}{3}$
There is no common ratio, so the sequence is not geometric.