Let `S_n` denote the sum of first n terms of a G.P. whose first term and common ratio are a and r
Channel: Doubtnut
Date: 2020-04-12

Let `S_n` denote the sum of first n terms of a G.P. whose first term and common ratio are a and r respectively. On the basis of above information answer the following question: `S_1+S_2+S_2+..+S_n=` (A) `(na)/(1-r)-(ar(1-^n))/((1-r)^20` (B) `(na)/(1-r)-(ar(1+^n))/((1+r)^20` (C) `(na)/(1-r)-(a(1-^n))/((1-r)^20` (D) none of these