已知方程组x+2y-z=0,2x-y+8z=0,求x*x+y*y+z*z/xy+yz的值_数学解答

已知方程组x+2y-z=0,2x-y+8z=0,求x*x+y*y+z*z/xy+yz的值

人气：199 ℃　时间：2020-06-03 06:52:38

解答

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