先一个一个的展开括号项,再同项合并就行了啊
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x
=[xx-xy-(xy-yy)+x(x-y)+y(x-y)]÷2x
=[xx-xy-xy+yy+xx-xy+xy-yy]÷2x
=(2xx-2xy)÷2x
=2x(x-y) ÷2x
=x-y
代入数值即可.xx是？x乘以x 啊。