Which sequences are geometric? Check all that apply. –2, –4, –6, –8, –10, … 16, –8, 4, –2, 1 –15, –18, –21.6, –25.92, –31.104, …

Presented sequences:

–2, –4, –6, –8, –10,...

16, –8, 4, –2, 1 , ......

–15, –18, –21.6, –25.92, –31.104, …

4, 10.5, 17, 23.5, 30, …

625, 125, 25, 5, 1, ….

Let's determine the ratios.

–2, –4, –6, –8, –10,...

The first sequence decreases by a constant difference of -2, indicating an arithmetic progression.

16, –8, 4, –2, 1 , ......

16 divided by -8 equals -2 and 4 divided by -2 equals -2.

Since the second sequence has a consistent ratio of -2, it qualifies as a geometric sequence.

–15, –18, –21.6, –25.92, –31.104, …

-18 divided by -15 is 1.2; -21.6 divided by -18 is 1.2.

This third sequence shares a common ratio of 1.2, so it is geometric.

4, 10.5, 17, 23.5, 30, …

10.5 divided by 4 is not equal to 17 divided by 10.5.

Since these ratios differ, this isn't a geometric sequence.

625, 125, 25, 5, 1, ….

125 divided by 625 equals 0.2, and 25 divided by 125 is also 0.2.

The fifth sequence features a common ratio of 0.2, making it geometric.