Question

Can you guys help me with this?

Answer 1

We have been given many sequences below:

The sequence is said to be geometric if there is same ratio between consecutive terms

`(a_n)/(a_(n-1))`

So we will check all the sequences one by one:

(1)
`(-9)/(-2.7)=(10)/(3)`

`(-30)/(-9)=(10)/(3)`

`(-100)/(-30)=(10)/(3)`.

Hence, geometric

(2)
`(2.5)/(-1)=-2.5`

`(-6.25)/(2.5)=-2.5`

`(15.625)/(-6.25)=-2.5`

Hence, geometric.

(3)
`(9.2)/(9.1)=0.010`

`(9.3)/(9.2)=0.010`

`(9.4)/(9.3)=0.010`

Hence, geometric.

(4)
`(0.8)/(8)=0.1`

`(0.08)/(0.8)=0.1`

`(0.008)/(0.08)=0.1`

Hence, geometric.

(5)
`(-4)/(4)=-1`

`(-12)/(-4)=3`

Ratio is not same hence, not geometric.