Here in this expansion (1+x)p+q The general term =Tr+1=p+qCr.(x)r ∴xp will be present in the term =p+qCp⋅(x)p So coefficient of xp=p+qCp And xq will be present in the term =p+qCq⋅(x)q ∴ coefficient of xq=p+qCq We know nCr=nCn−r ∴p+qCq=p+qC(p+q)−q=p+qCp So coefficients of xp and xq are equal.