﹙x-y﹚﹙x+2y﹚-﹙x+2y﹚²的解和过程

问题描述:

﹙x-y﹚﹙x+2y﹚-﹙x+2y﹚²的解和过程

=x(x+2y)-y(x+2y)-(x^2+2xy+y^2)=x^2+2xy-xy-2y^2-x^2-2xy-y^2=x^2-xy-3y^2