计算：（-3m+4n）^2
问题描述：
计算：（-3m+4n）^2
答
=9m^2-24mn+16n^2
答
是 16n^2-24mn+9m^2
答
（-3m+4n）^2
=(-3m)^2+2*(-3m)*4n+(4n)^2
=9m^2-24mn+16n^2
答
（-3m+4n)^2=9m^2-24mn+16n^2