Class 10 Maths Formulas For Arithmetic Progression (AP)

If a1, a2, a3, a4….. be the terms of an AP and d be the common difference between each term, then the sequence can be written as: a, a + d, a + 2d, a + 3d, a + 4d…… a + nd. where a is the first term and (a + nd) is the (n – 1) th term. So, the formula to calculate the nth term of AP is given as:
nth term = a + (n-1) d
The sum for the nth term of AP where a is the 1st term, d is the common difference, and l is the last term is given as:
Sn = n/2 [2a + (n-1) d] or Sn = n/2 [a + l]