Question

if a,b,c,d are the A.P then prove that (d-b) is equal to(c-a)

Answer 1

let us assume
the common difference between a, b is D

a, b, c, d
the difference d-c=D
c-b=D
like that
d-b=2D----------1
c-a=2D---------------2
from 1&2
rhs are equal so lhs should be equal
there fore d-b=c-a

hence proved