3X-4Y-Z=0,2X+Y-8Z=0
=>
X=31Z/5
Y=-22Z/5
代入要求代数式,
(X^2+Y^2-Z^2)/(XY+YZ)=[(31/5)^2+(-22/5)^2-1]/[(31/5)(-22/5)+(-22/5)]=1444/792~=1.82