PLEASE HELP ASAP
What are the explicit equation and domain for a geometric sequence with a first term of 3 and a second term of −9?

an = 3(−12)n − 1; all integers where n ≥ 1
an = 3(−12)n − 1; all integers where n ≥ 0
an = 3(−3)n − 1; all integers where n ≥ 1
an = 3(−3)n − 1; all integers where n ≥ 0

So then we have this:

And using the second term we have:

And solving for the value of r we got:

So then our general expression for this geometric sequence would be:

And the best answer would be:

an = 3(−3)n − 1; all integers where n ≥ 1

Step-by-step explanation:

For this case we need to remember that the general formula for a geometric sequence is given by:

And for this case we have the following values for the sequence given:

So then we have this:

And using the second term we have:

And solving for the value of r we got:

So then our general expression for this geometric sequence would be:

And the best answer would be:

an = 3(−3)n − 1; all integers where n ≥ 1