x2+y2+z2-2xy+2yz+2zx=?

分类: 作业答案 • 2022-01-09 18:01:57

问题描述：

答

x^2+y^2+z^2-2xy+2yz+2zx
=(x^2-2xy+y^2)+2(x+y)z+z^2
=(x-y)^2+2(x+y)z+z^2
=(x-y+z)^2