Question

The sum of the first three terms of a G.P. is 21/2 and their product is 27. Find the common ratio.

• A. 2, 1/2
• B. 3, 1/3
• C. 2,4
• D. 1, 1/2

Answer 1

Answer:

A. 2, 1/2

Let the terms be a/r, a, ar a/r × a × ar = 27 a³ = 27 a = 3 a/r + a + ar = 21/2 a(1/r + 1 + r) = 21/2 (1 + r + r²) = 7r/2 on solving r = 2 or 1/2