How do you write an explicit formula for the sequence ? 640,160,40,10,..

1 Answer
Feb 26, 2018

an=640(14)n1

Explanation:

This is a geometric sequence; the ratio of two consecutive terms is the same:

160640=14

40160=14

1040=14

The explicit or general formula of a geometric sequence is

an=a1rn1 with a1 as the first term, r as the common ratio, and n as the nth term.

Plug in:

an=640(14)n1

Double Check:

a2=640(14)21=6404=160