Let P(n) be the given statement, i.e.
⇒ P(1) is true.
We note than P(n) is true for n = 1.
Assume that P(k) is true
Now, we shall prove that P(k + 1) is true whenever
P(k) is true. We have,
∴ P(k + 1) is also true whenever P(k) is true
Hence, by the principle of mathematical induction, P(n) is also true for all n ∈ N.