Which sequences are geometric sequences? 4, 2, 1,1/2,1/4,... −2, 3, −4, 5, −6, … 2, 6, 18, 54, 162, … −4, −16, −64, −256, … −2, −4, −12, −48, −240, …

first one: 4, 2, 1,1/2,1/4

third one: 2, 6, 18, 54, 162

fourth one: −4, −16, −64, −256

Step-by-step explanation:

To know if a sequence is a geometric sequence, we divide a term by the term that goes before, and the resulting value will be the ratio and need to keep working on the next divisions of terms by the terms before.

Let's check each sequence:

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

2/4 = 0.5

1/2 = 0.5

1/2 / 1 = 0.5

1/4 / 1/2 = 0.5

This sequence is a geometric sequence, with ratio = 0.5

−2, 3, −4, 5, −6

3/-2 = -1.5

-4/3 = -1.333

This is not a geometric sequence

2, 6, 18, 54, 162

6/2 = 3

18/6 = 3

54/18 = 3

162/54 = 3

This sequence is a geometric sequence, with ratio = 3

−4, −16, −64, −256

-16/-4 = 4

-64/-16 = 4

-256/-64 = 4

This sequence is a geometric sequence, with ratio = 4

−2, −4, −12, −48, −240

-4/-2 = 2

-12/-4 = 3

This is not a geometric sequence

the workers who do no drive has no reasonable reason to buy gasoline due to they don't have anything to use it for

i think the answer is b