(2分之1m-3分之1n^2)^2
问题描述：
(2分之1m-3分之1n^2)^2
答
(m/2-n^2/3)^2
=m^2/4+n^4/9-mn^2/3
(2分之1m-3分之1n^2)^2
(m/2-n^2/3)^2
=m^2/4+n^4/9-mn^2/3