CBSE Class 9 Answered

An arithmetic progression (A.P) or arithmetic sequence is a sequence in which the difference between any two consecutive terms is constant. The difference between the consecutive terms is known as the common difference and is denoted by d. 

Example:

The given sequence is in A.P:  1, 3, 5, 7, 9, 11.

Here, d = 3 – 1 = 2, 5 – 3 = 2

So, we can see that the difference is common to both the terms. So, we can say that the given sequences are in arithmetic progression.