If Sn, the sum of first n terms of an A .P. is given by Sn = 5n2 + 3n, then find its nthterm.
Sn = 5n2 + 3n
Find the sum of the :
(i) First 25 terms of an A .P. whose nth term is given by an= 7 – 3n
The sum of the first p, q and r terms of an A .P. are a, b, c respectively.
Prove that
If in sin A .P. the sum of m terms is equal to n and the sum of n terms is equal to m, then prove that the sum of (m + n) terms is –(m + n).