Prove the following using the principle of mathematical induction for all n ∈ N

1.3 + 3.5 + 5.7 +…+(2n – 1)(2n + 1)=

Let the given statement be P(n), as

First, we check if it is true for n = 1,

∴ It is true for n = 1.

Now we assume that it is true for some positive integer k, such that

…………..(1)

We shall prove that P(k + 1)is true,

Solving the left hand side with n = k + 1

[From equation (1)]

Which is equal to the Right hand side for n = k + 1.We proved that P(k + 1) is true.

Hence by principle of mathematical induction it is true for all n ∈ N.