[" Ems is the sum of its first three terms "],[" turg "],[" the sum of all the terms of the A.P.is "(n)/(6)(x+y)" ."]

An A.P. consists of n terms. If the sum of its first three terms is x and the sum of the last three terms is y, then show that, the sum of all the terms of the A.P. is (n)/(6)(x+y) .

In the sum of first n terms of an A.P.is cn^(2), then the sum of squares of these n terms is

The sum of the first n terms of an A.P.is 4n^(2)+2n. Find the nth term of this A.P.

If the n^(th) term of an A.P.is (2n+1), find the sum of first n terms of the A.P.

If the first term of an A.P. is 100 and the sum of its first 6 terms is five times the sum of the next 6 terms then its common difference is

Let the sum of the first three terms of an A.P be 39 and the sum of its last four terms be 178. Ifthe first term of this A.P.is 10, then the medianof the A.P.is

The sum of first n terms of an A.P is given by 3n^(2)+6n The 22 nd term of the A.p.is

The sum of first three terms of a G.P. is 15 and sum of next three terms is 120. Find the sum of first n terms.

191.If the sum of first n terms of an A.P.is Zero,then the sum of next m terms,where a is the first term of the A.P.is