Question

If first term of an A.P. is a, second term is b and last term is c, then show that sum of all terms is \( \frac{ (a + c)(b + c - 2a )}{2(b-a)}\)

Answer 1

proof:

i. t₁ = a, t₂ = b, t_n = c     .....[Given]

∴ d = t₂ - t₁ = b - a