The sum of n terms of `(1-1/n) + (2-4/n) + (3-9/n) +.....`​

find the sum of n terms: a(n) = n(n+1)-2

If the sum of n terms of sequence S_(n)=(n)/(n+1)

.The sum to 'n' terms of the series 9 + 99 + 999 ... ... is ] , [ 1) (10 ( 10^ n − 1 ) − n) 2) (10/ 9 [ 10^ n − 1 ] + n) 3) (10/ 9 [ 10^ n − 1 ] − n) 4) (10/ 9 [ 10^ n − 1) ]

Show that the ratio of the sum of first n terms of a G.P. to the sum of terms from (n+1) to (2n) terms is (1)/(r^(n))

If the sum of n terms of an A.P is (4n^(2)-3n)/(4) then ,n^(th) term of the A.P

Find the sum of n terms of the series (1)/(2*4)+(1)/(4*6)+... (A) (n)/(n+1) (B) (n)/(4(n+1)) (C) (1)/((2n)(2n+2))( D) )(1)/(2^(n)(2^(n)+2))

find the sum of n terms of the series (4-(1)/(n))+(4-(2)/(n))+(4-(3)/(n))+