= (n+1).

Let P(n) = = (n+1)
P(1) is true.
Assuming P(k) is true.
P(k) = = K+1
To prove P(k+1) is true.
P(k+1) = = K+2………….(1)
L.H.s of (1)
= (k+1)1+
= = K+2
Which is the R.H.S of (1)
P(K+1) is true.
By the Principle of mathematical induction, P(n) is true for all values of n where n N
Hence proved.