Prove that
for all natural
numbers, n ≥ 2.
Let P(n) =
Let us find if it is true at n = 2,
P(2):
P(2):
Hence, P(2) holds.
Now let P(k) is true, and we have to prove that P(k + 1) is true.
Therefore, we need to prove that,
P(k) = …….(1)
Taking L.H.S of P(k) we get,
P(k) =
P(k + 1) =
From equation (1),
P(k + 1) =
P(k + 1) =
P(k + 1) =
P(k + 1) =
Therefore, P(k + 1) holds.
Hence, P(n) is true for all n ≥ 2.