Find the common ratio in a geometric sequence where the first term is 2/5 and the third term is 1/10

Question

Mathematics

Jazlynn

29 December, 16:29

Find the common ratio in a geometric sequence where the first term is 2/5 and the third term is 1/10

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Answers (1)

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Francesca Hicks · Answer 1

GP is given by = arⁿ⁻¹

First term of GP = 2/5, a = 2/5 ... (i)

Third term = 1/10, ar² = 1/10 ... (ii)

(ii) : (i)

ar² : a = (1/10) : (2/5)

r² = 1/10 * 5/2

r² = 1/4 Take square root of both sides

r = √ (1/4)

r = 1/2.

Common ratio = 1/2.