Represent the geometric series using the explicit formula.
12, −36, 108, −324, …
f(n) = f(n − 1) ⋅ (−3)
f(n) = f(n − 1) ⋅ (3)
f(n) = 12 ⋅ (−3)(n−1)
f(n) = 12 ⋅ (3)(n−1)

Step-by-step explanation:

The Explicit formula in function notation for a geometric series is:

Where is the nth term of the sequence, is the first term in the sequence and is the common ratio.

Given the following geometric serie:

The common ratio is:

And the first term is:

Therefore, substituting values, we get that the Explicit formula that represents this geometric series is:

you can't solve x because it is 2 linear equation and you only have one equation