Please help, 70 points 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)

Aletter in the word electric is chosen at random. complete each sentence. there are possible outcomes. the theoretical probability that a vowel will not be chosen is the ratio . the theoretical probability that the letter n will be chosen is .