The first term of a geometric sequence is 9 and the common ratio is -1 over 3. find the fourth term

Answer 1

use your definitions

fourth term = ar^3
= 9(-1/3)^3
= 9(-1/27)
= -1/3

or
simply list the first 4 terms to see the 4th term

9, -3, 1, -1/3, ...