9. Determine which of the following sequences is a geometric sequence. Check all that apply. 3,9, 27, 81, ...
100, 90, 80, 70, ...
5, 10, 20, 40, ...
2, 10, 18, 26,...
625, 125, 25, 5, ...
-2, 6, -18, 54, ...

Step-by-step explanation:

first geometric sequence

3^1, 3^2 ,3^3, 3^4,

3, 9, 27, 81

second

5^1, 5^2, 5^3, 5^4,

5, 25, 125, 625,

third

2, 10, 18, 26,

which has the difference of 8

fourth

100, 90, 80, 70,

you didn't give me the choices, so i will just give you the graph so you can look at your choices and choose the right one.