Out of the options given what is the answer?

Question

Given a geometric sequence in the table below, create the explicit formula and list any restrictions to the domain.

nan
1	−4
2	20
3	−100

 a_n = −5(−4)^{n − 1} where n ≥ 1

 a_n = −4(−5)^{n − 1} where n ≥ 1

 a_n = −4(5)^{n − 1} where n ≥ −4

 a_n = 5(−4)^{n − 1} where n ≥ −4

Answer 1

The sequence -4, 20, -100, ... is geometric with common ratio r = -5

The nth term, a_n , is given by the formula a_n = a₁r^n-1 = -4(-5)^n-1, where n ≥ 1

Answer 2

First, note that the value where n = 1 is simply 4-*n⁰ , which is -4.

Next, note that, for each increment of n, the value is multiplied by -5. That is what is meant by (-5)^(n-1)

There is only one choice that is consistent with the above two statements