已知方程组x+2y-z=0,2x-y+8z=0,求x*x+y*y+z*z/xy+yz的值
问题描述：
已知方程组x+2y-z=0,2x-y+8z=0,求x*x+y*y+z*z/xy+yz的值
答
x+2y-z=0,2x-y+8z=0,
可知
x=-3z y=2z
所以
x*x+y*y+z*z/xy+yz
=(9z^2+4z^2+z^2)/(-6z^2+2z^2)
=(14z^2)/(-4z^2)
=-7/2