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Question
For a G.P. if a = 2, r = 3, Sn = 242 find n
Solution
a = 2, r = 3, Sn = 242
Sn =
∴ 242 =
∴ 242 = 3n – 1
∴ 3n = 243
∴ 3n = 35
∴ n = 5
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