Sum Of The First n Terms Of An Arithmetic ProgressionThe sum of first n terms of an A.P. is given by Sn = n/2 [2a + (n – 1) d] or Sn = n/2 [a + Tn] Note: (i) If sum of n terms Sn is given then general term Tn = Sn – Sn-1 where Sn-1 is sum of (n – 1) terms of A.P. (ii) nth term of an AP is linear in ‘n’ Example: an = 2 – n, an = 5n + 2 …….. Also we … [Read more...] about Sum Of The First n Terms Of An Arithmetic Progression