The common difference of an A.P., the sum of whose n terms is Sn, is

1.	The common difference of an A.P., the sum of whose n terms is Sn, is A. Sn – 2Sn–1 + Sn–2 B. Sn – 2Sn–1– Sn–2 C. Sn – Sn–2 D. Sn – Sn–1
Answer» a_n is the n^th term of an A.P and a_n–1 is the (n–1)^th term of an A.P, d = common difference, S_n = sum of n terms of an A.P d= a_n – a_n–1 But a_n= S_n – S_n–1 And a_n–1= S_n–1 – S_n–2 So d= S_n – S_n–1 – (S_n–1 – S_n–2) d= S_{n – 2} S_n–1 + S_n–2

The common difference of an A.P., the sum of whose n terms is Sn, is A. Sn – 2Sn–1 + Sn–2 B. Sn – 2Sn–1– Sn–2 C. Sn – Sn–2 D. Sn – Sn–1

Answer»

a_n is the n^th term of an A.P and a_n–1 is the (n–1)^th term of an A.P,

d = common difference,

S_n = sum of n terms of an A.P

d= a_n – a_n–1

But a_n= S_n – S_n–1

And a_n–1= S_n–1 – S_n–2

So d= S_n – S_n–1 – (S_n–1 – S_n–2)

d= S_{n – 2} S_n–1 + S_n–2