你好 （x+y-z）*（x+y-z)-(x-y+z)*(x-y-z)=[（x+y）-z]*[（x+y）-z]-[(x-y）+z]*[(x-y）-z)]=[（x+y）²-z²]-[（x-y）²-z²]=（x+y）²-（x-y）²=4xy 【数学辅导团】为您解答,不理解请追...