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

User Rayfleck
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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.
User Maximas
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