Question

The sum of n, 2n,3n terms of AP S1 ,S2 ,S3 respectively. Prove that S3=3(S2-S1)

Answer 1

Step-by-step explanation:

(3n/2)(2a+(3n-1)d)=3((2n/2)(2a+(2n-1)d)-(n/2)(2a+(n-1)d))

simplifying this would give us

6a+9nd-3d=6a-3d+9nd

hence proved

hope this helps...

Answer 2

plz refer to this attachment