Which sequences are geometric? check all that apply.

–2.7, –9, –30, –100,

–1, 2.5, –6.25, 15.625,

9.1, 9.2, 9.3, 9.4,

8, 0.8, 0.08, 0.008,

4, –4, –12, –20,

The correct answers are:

–1, 2.5, –6.25, 15.625, ... ; and 8, 0.8, 0.08, 0.008, ...

Explanation:

A geometric sequence is one in which every term is found by multiplying the previous term by a constant.

In the sequence -1, 2.5, -6.25, 15.625, ..., each term is found by multiplying the previous term by -2.5.

In the sequence 8, 0.8, 0.08, 0.008, ..., each term is found by multiplying the previous term by 0.1.