2x-3y+3z=0 (1)
3x-2y-6z=0 (2)
(1)*2+(2)
7x-8y=0
y=7x/8
2x-21x/8+3z=0
z=5x/24
原式=(1+49/64+25/576)/(2+49/64+25/576)=521/809