S_1,S₂,S₃ are the sum of n,2n.3n terms respectively of an A.P then

a.S₃=S₁+S₂

b.S₃=2(S₁+S₂)

c.S₃=3(S₂-S₁)

d.non of these

Hi Student
a= first term l=last term
S1= n/2(a+l)
S2=2n/2(a+l)= n(a+l)
S3= 3n/2(a+l) = n(a+l) + n/2(a+l) =S1+ S2

Clearly option A satisfies this.
….….….….….….….….…...