[" What the sum of an "AP" whose first term is "a" ,the second term "b" and the last term "c" ,is equal to "],[qquad 2(b-a)]

Show that the sum of an AP whose first term is a, the second term is b and the last term is c is equal to ((a+c)(b+c-2a))/(2(b-a)) .

Show that the sum of an AP whose first term is a, the second term b and the last term c, is equal to ((a+c)(b+c-2a))/(2(b-a)) .

Show that the sum of an AP whose first term is a, the second term b and the last term c, is equal to ((a+c)(b+c-2a))/(2(b-a)) .

Show that the sum of an A.P. whose first term is a, the second term is b and the last term is c, is equal to ((a+c)(b+c−2a))/(2(b−a))

Show that the sum of an A.P.whose first term is a,the second term is b and the last term is c,is equal to '((a+c)(b+c-2a))/(2(b-a))

In a G.P.the first term isa,second term is b and the last term is c then sum of the series is

What is the sum of first ten terms of the A.P., if the first term is 1 and the last term is 19 ?

Find the sum of first 20 terms of an A.P. whose first term is 3 and the last term is 57.

What is the sum of first six terms of an A.P. whose first term is 3 and the sixth term is 27.

Find the sum of the first 51 terms of the A.P.: whose second term is 2 and fourth term is 8.