Arithmetic Progression (AP)
Definition
A sequence of numbers in which each term after the first is obtained by adding a fixed constant (called the Common Difference, d) to the preceding term. The general term is Tn = a + (n−1)d, and the sum is Sn = n/2 × [2a + (n−1)d].
Example
"The sequence 2, 5, 8, 11, 14... is an AP with first term a = 2 and common difference d = 3. The 10th term = 2 + (10−1)×3 = 29."