设3/x=1/y/=2/z=k,则,x=3/k,y=1/k,z=2/k
代人,得,
(2x²-2y²+5z²)/(xy+yz+xz)
=(18/k²-2/k²+20/k²)/(3/k²+2/k²+6/k²)
=(36/k²)/(11/k²)
=36/11
设3/x=1/y/=2/z=k,则,x=3/k,y=1/k,z=2/k
代人,得,
(2x²-2y²+5z²)/(xy+yz+xz)
=(18/k²-2/k²+20/k²)/(3/k²+2/k²+6/k²)
=(36/k²)/(11/k²)
=36/11