Answers

2016-03-14T16:44:41+05:30
Since the formula of sun of nth term in A.P is n/2{2a+(n-1)d}nowS1=n/2{2a+(n-1)d}S2=2n/2{2a+(2n-1)d}S3=3n/2{2a+(3n-1)d}S2-S1=n/2{2a+(3n-1)d}
therefore3(S2-S1)=3n/2{2a+(3n-1)d}=S3
hpe i helped u plz mark as brainiest answer plz
1 5 1
there is gaps in between them i cannot edit