General terms
* Arithmetic Progression (AP) is a sequence in which the difference between any two successive terms is constant, which is referred to as the Common Difference.
* An AP either increases or decreases progressively.
Common Difference = any term –Preceding term
General term of an AP: t_{n} = a + (n – 1)d
where,
* t_{n} = nth term of the AP
* n = number of terms in the AP
The number of terms of an AP: n = \frac{ t_{n} - a}{d} + 1
Sum of n Terms
Sum of n terms in AP is :
S = \frac{n}{2} [ 2a + (n - 1) ]
(or)
S = \frac{n}{2} [first term + last term]