x-y+z=0,x+y-5z=o,xyz≠0,求x^2+y^2+z^2/2x^2+y^2-z^2的值

来源：学生作业帮编辑：神马作文网作业帮分类：数学作业时间：2024/11/18 14:20:38

x-y+z=0````````````````````1
x+y-5z=o``````````````````2
联立1、2解得：
y=3z, x=2z
(x^2+y^2+z^2)/(2x^2+y^2-z^2)
=[(2z)^2+(3z)^2+z^2]/[2(2z)^2+(3z)^2-z^2]
=14z^2/16z^2
=7/8
再问：我算出来好像不是7/8啊

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