Question

Show that a-b, a, a+b form consecutive terms of an A.P.

Answer 1

here, a-b is a1, a is a2 and a+b is a3
so,
d1 = a2-a1 = a-(a-b) = a-a+b = b
and,
d2 = a3-a2 = (a+b)-a = a+b-a = b
here,
d1=d2
hence, a-b, a and a+b are in AP.

Answer 2

I hope this will satisfy you