[" If denotes the sum of first 'n' "],[" natural numbers,then "],[S_(1)+S_(2)x+S_(x)^(2)+....+S_(x)x^(n-1)+...oo]

If S_(n) denotes the sum of first 'n' natural numbers then S_(1)+S_(2)x+S_(3)x^(2)+........+S_(n)*x^(n-1)+.....oo= then n is

If S_(n) denotes the sum of first n naturalnumbers, then S_(1)+S_(2)x+S_(3)x^(2)+.......+S_(n)x^(n-1)+....oo=

If s_(n) denotes the sum of first 'n' natural numbers then S_(1)+S_(2)x+S_(3)x^(2)+.........+S_(n)x^(n-1)+......oo=(1-x)^(-n) then n is

If S_(n) denotes the sum of first 'n' natural numbers then s_(1)+S_(2)x+S_(3)x^(2)+.........+S_(n) x^(n-1)+......oo=(1-x)^(-n) then n is

If S_(n) denotes the sum of first 'n' natural numbers then S_(1)+S_(2)x+S_(3)x^(2)+........+S_(n)*x^(n-1)+.. then n is

If S_(n) denotes the sum of first 'n' natural numbers then S_(1)+S_(2)x+S_(3)x^(2)+........+S_(n)*x then n is

If S_n denotes the sum of first n natural number then S_1 + S_2x + S_3 x^2 +……+S_n x^(n-1) + ……oo terms =

If S_n denotes the sum of first n natural number then S_1 + S_2x + S_3 x^2 +……+S_n x^(n-1) + ……oo terms =

Let S_(n) denote the sum of the cubes of the first n natural numbers and s_(n) denote the sum of first n natural numbers then (S_(n))/(s_(n)) is equal to (i) (n(n+1)(n+2))/6 (ii) (n( n+1))/2 (iii) (n^(2)+3n+2)/2 (iv) (2n+1)/3

If S_(n) denotes the sum of first n terms of an A.P., then (S_(3n)-S_(n-1))/(S_(2n)-S_(n-1)) is equal to