Answer
Geometric with a common ratio of$-2$.
Work Step by Step
Check if there is a common ratio by diving each pair of consecutive terms:
$\dfrac{-2}{1}$ $=-2$;
$\dfrac{4}{-2}$ $=-2$ ;
$\dfrac{-8}{4}$ $=-2$.
The ratio is constant so the sequence is geometric.
The common ratio is $-2$.