Question

If Sn denotes the sum of the first n terms of an A.P .,then S2-S1=----

Answer 1

Answer:

Step-by-step explanation:

S2=a+a+d=2a+d

S1=a

S2-S1=2a+d-a

a+d=second term of A.P series

this an important formula

Sn-Sn-1=tn=nth term of A.P series