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Question
Answer the following:
If for a G.P. t3 = `1/3`, t6 = `1/81` find r
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Solution
Given, t3 = `1/3`, t6 = `1/81`
tn = arn–1
∴ t3 = ar2
∴ ar2 = `1/3`
∴ a = `1/(3"r"^2)` ...(i)
Also, t6 = ar5
∴ ar5 = `1/81`
∴ `1/(3"r"^2) xx "r"^5 = 1/81` ...[From (i)]
∴ r3 = `1/27`
∴ r = `1/3`
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