=a^m*a^(- 1)*a^(n+2)+a^(m+2)+a^m*a^(n+ 1)
=a^ma^(n+ 1)+a^(m+2)+a^m*a^(n+ 1)
=2a^ma^(n+ 1)+a^2*a^m
=a^m*[2a^(n+ 1)+a^2]