答：
式子不完全啊...
（2m＋3n)(-2m+3n)－(3m-2n)^2
=(3n)^2-(2m)^2-[(3m)^2-12mn+(2n)^2]
=9n^2-4m^2-9m^2+12mn-4n^2
=5n^2+12mn-13m^2