计算(x-y)的2次方减(x+y)的2次方

问题描述:

计算(x-y)的2次方减(x+y)的2次方

答案是:-4xy

结过是负4XY

(x-y)^2-(x+y)^2
=x^2-2xy+y^2-x^2-2xy-y^2
=-4xy

(x-y)^2-(x+y)^2
=x^2-2xy+y^2-x^2-2xy-y^2
=-4xy