# How do you know if the sequence 1, -2, -5, -8,... is arithmetic or geometric?

Dec 1, 2016

It is an arithmetic sequence

#### Explanation:

It is an arithmetic sequence because:

${a}_{n} - {a}_{n - 1} = - 3 \forall n$

that's

$- 2 - 1 = - 5 - \left(- 2\right) = - 8 - \left(- 5\right) \ldots = - 3$