In the binomial expansion of `(1+a)^(m+n)` , prove that the coefficient of `a^m a n d\ a^n` are equal.

Explanation

In the binomial expansion of `(1+a)^{m+n}`,

we have

`A=` Coefficient of `a^{m}=\ ^{m+n} C_{m}=frac{(m+n) !}{m ! n !}`

and `B=` Coefficient of `a^{n}=\ ^{m+n} C_{n}=frac{(m+n) !}{m ! n !}`

Clearly, A = B