Prove the following by principle of mathematical induction for all :
Let
I. For n = 1,
∴ P(1) is true
II. Suppose the statement is true for n = m,
∴
III. For n = m +1,
or
∴
which is true
∴ P(m + 1) is true
∴ P(m) is true P (m + 1) is true
Hence, by the principle of mathematical induction, P(n) is true for all