Question

If a2= 18 and a4= 8, find two possible common ratios. Then, write two sequences lhaving five terms each.

Answer 1

common ratio = a4/a3 = a3/a2

8/a3 = a3/18

(a3)^2 = 8 * 18

(a3)^2 = 144

a3 = 12 or a3 = -12

common ratio = 8/12 or common ratio = 8/(-12)

common ratio = 2/3 or common ratio = -2/3

Answer: 12 or -12