S1,S2,S3....Sn is the sum of an infinite GP with first terms as 1,2,3....n and common ratios as 12,13....1n+1 then find S1+S2+S3....+Sn
S1=2
S2=3
S1+S2=5
Here n=2
Go from answer options
n(n+1)=2.3 =6
12n2=12×4=2
12n(n+3)=12(2)(5)=5
n=2
n2=4