Help writing the explicit formula

Write explicit formula, find 5th term
a1= 3
r= -3

Geometric sequence formula:

An = A₁r^(n - 1)

You have A₁ = 3, r = -3.
An = (3)(-3)^(n - 1)

Since we also know that we're finding the 5th term, so n = 5, and thus we're trying to find A₅:
A₅ = (3)(-3)^(5 - 1)
A₅ = (3)(-3)^4
A₅ = (3)(81)
A₅ = 243

Thus, the 5th term is 243.

Hope this helps :D

hint:
3 x r^4 =a5