Which sequences are geometric sequences? Check all that apply

4, 2, 1, 1/2, 1/4 ...

2, 6, 18, 54, 162 ...

-4, - 16, - 64, - 256 ...

Those are the geometric sequences because the factor is 1/2.

4/2=2

2/2=1

And so on,

The first one has a factor of three and the second has a factor of four.