In the binomial expansion of (1+a)m+n n, if the coefficients of am and an are A and B respectively, then
A =B
mA =nB
nA =mB
A =2B
In the binomial expansion of (1+a)n+n ,we have
A = Coefficient of am=m+nCm=(m+n)!m!n!
and ,
B = Coefficient of an=m+nCn=(m+n)!m!n!
Clearly, A = B.