关于火烧圆明园的笑话:一道计算题(过程)

来源:百度文库 编辑:中科新闻网 时间:2024/05/05 11:01:16
(x^2-2xy+y^2-4)÷(x-y+2)

=(x^2-2xy+y^2-4)÷(x-y+2)=[(x-y)^2-2^2])÷(x-y+2)=(x-y+2)(x-y-2)÷(x-y+2)=x-y-2

(x^2-2xy+y^2-4)÷(x-y+2)=[(x-y)^2-4]÷(x-y+2)
=(x-y+2)(x-y-2)÷(x-y+2)
=x-y-2
利用了平方差公式,将4看成2的平方