Question

Please check out the following attachment
JEE advanced previous year question

Answer 1

Hi mate nice question.... Atq : Sn = 0[n-n-1] + (a[n^2- (n-1)^2] )/2

=[ a+n^2-(n^2+1-2n)]/2.

= a(2n-1) / 2. Sn+1= a([n+1]^2-n^2) /2 = a(2n+1)/2 ...... Then Sn/ Sn+1= 2n-1/ 2n+1...