Question
2 + `2^2` + `2^3` +...........+ `2^9` = ?
Answer: Option B
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This is a G.P. in which a = 2, r= `2^2/2` = 2 and n = 9.
`s_n` = `[a(r^n -1)]/[(r-1)]` = `[2 xx (2^9 - 1)]/[(2 - 1)]` = 2 x (512 - 1) = 2 x 511= 1022
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