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In a GP, the sum of the first three terms is 13/12 and their product is −1. The common ratio is
A−1/2
B−3/4 or −4/3
C1/2
D2
Answer & Solution
Correct answer: B. −3/4 or −4/3
Take terms a/r, a, ar. Product = a³ = −1 ⇒ a = −1. Sum: −1/r − 1 − r = 13/12 ⇒ 12r² + 25r + 12 = 0 ⇒ r = −3/4 or −4/3.
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