The first term of a Geometric Progression (GP) is \(\frac{3}{4}\), If the product of the second and third terms of the sequence is 972, find its common ratio.

  • A 3
  • B 4
  • C 6
  • D 12
waec 2018furthermathematics

The correct answer is D. 12

Recall, the terms of a GP is given by \(T_{n} = ar^{n - 1}\)

Given, \(T_{1} = a = \frac{3}{4}\) and \(T_{2} \times T_{3} = ar \times ar^{2} = 972\)

\(\implies \frac{3}{4}r \times \frac{3}{4}r^{2} = \frac{9}{16}r^{3} = 972\)

\(r^{3} = \frac{972 \times 16}{9} = 1728  \implies r = \sqrt[3]{1728} = 12\)

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