Answer
The sequence is geometric. The common ratio is $2$.
Work Step by Step
\ltIn order to determine whether or not a sequence is geometric, we need to find out if there is a common ratio between the terms:
$r = \frac{20}{10} = 2$
$r = \frac{40}{20} = 2$
The ratios between the terms are the same; therefore, there is a common ratio, and the sequence is, thus, geometric. The common ratio is $2$.
