Find an explicit formula for the arithmetic sequence 81,54,27,0,...

Question

asked Feb 9, 2021 186k views

2 Answers

Infinity · Answer 1 · 2021-02-13T23:07:27+0000

Answer:

an = -27n + 108.

Explanation:

The first term a1 = 81 and the common difference d = 54-81 = -27 . (Also 27 - 54 = -27 and 0 - 27 = -27).

The explicit formula is

an = a1 + d(n - 1)

= 81 - 27(n - 1)

= -27n + 81 + 27

= -27n + 108.