已知m^2-mn=37,mn-n^2=-12,求m^2-n^2和m^2-2mn+n^2的值.
问题描述:
已知m^2-mn=37,mn-n^2=-12,求m^2-n^2和m^2-2mn+n^2的值.
答
应该是:
m^2-n^2=37+12=49
m^2-2mn+n^=37-12=25【完】
求顶!我要详细的过程啊!!!∵m^2-mn=37 ①;mn-n^2=-12 ②∴由①+②得:m^2-n^2=37+(-12)=25由①-②得:m^2-2mn+n^2=37-(-12)=49∴m^2-n^2的值是25;m^2-2mn+n^2的值是49