计算(x+2y-z)(2y+z-x)
问题描述：
计算(x+2y-z)(2y+z-x)
答
4y^2-X^2+2XZ-Z^2
答
(x+2y-z)(2y+z-x)=(2y+x-z)(2y-x+z)=4y^2-(x-z)^2=4y^2-x^2+2xz-z^2
答
原式=[2y+(x-z)]*[2y-(x-z)]
=4y^2-(x-z)^2
=4y^2-x^2+2xz-z^2
答
=2xy+xz-x^2+4y^2+2yz-2xy-2zy-z^2+xz
=-x^2+4y^2-z^2+2xz