(x一2y+z)(-x+2y+z)(计算)
问题描述：
(x一2y+z)(-x+2y+z)(计算)
答
=-(x-2y+z)(x-2y-z)
=-(x-2y)^2-z^2
(x一2y+z)(-x+2y+z)(计算)
=-(x-2y+z)(x-2y-z)
=-(x-2y)^2-z^2