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प्रश्न
For the following G.P.s, find Sn
3, 6, 12, 24, ...
उत्तर
3, 6, 12, 24, …
Here, a = 3, r = `6/3` = 2 > 1
Sn = `("a"("r"^"n" - 1))/("r" - 1)`, for r > 1
∴ Sn = `(3(2^"n" - 1))/(2 - 1)`
Sn = 3(2n – 1)
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