Answer:
a(n) = 27*(2/3)^(n - 1)
Step-by-step explanation:
The first four terms are 27, 18, 12, 8.
Find the common ratio:
To do this, let that ratio = r, and write and solve 27r = 18. Thus, r = 2/3.
The general explicit formula for this sequence is
a(n) = a(1)*(2/3)^(n - 1), or, since a(1) = 27, a(n) = 27*(2/3)^(n - 1)
