CBSE Class 10 Maths (Standard) 2020 · Paper 30/2/1 · Question 28(a)

Arithmetic Progressions 3 marks Medium

Show that the sum of all terms of an A.P. whose first term is

a

, the second term is

b

and the last term is

c

is equal to

\frac{( a + c ) ( b + c - 2 a )}{2 ( b - a )}

Answer

S = \frac{( a + c ) ( b + c - 2 a )}{2 ( b - a )}

, as required.

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