If the sum of first m terms of an A.P. be n and sum of first n terms be m, then show that the sum of its first (m+n) terms is -(m+n).

If the 'sum of first m terms of an A . P . be n and the sum of first n terms be m , show that the sum of first m+n terms is -(m+n)

If the sum of first n terms of G.P. is S and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S.

If the sum of first n terms of a G.P. is s and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S .

If the sum of first n terms of a G.P. is S and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S.

If the sum of first m terms of an A.P.is the same as the sum of its first n terms,show that the sum of tis (m+n) terms is zero.

If the sum of first m terms of an A.P is n and sum of first n terms of the same A.P is m, show that sum of first (m+n) terms of it is -(m+n) .

If the sum of first m terms of an A.P. is the same as the sum of its first n terms, show that the sum of its (m+n) terms is zero.

If the sum of first m terms of an A.P. is the same as the sum of its first n terms, show that the sum of its (m+n) terms is zero.

If the sum of first m terms of an A.P. is the same as the sum of its first n terms, show that the sum of tis (m+n) terms is zero.

The sum of first n terms of an A.P. is m and that of first m terms is n. Prove that the sum of first m + n terms is -(m + n) .