已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________

已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________
已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________

已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________
1.由x+2y-7z=0得x=7z-2y
2.把它代入4x-3y-6z=0,得2z=y
3.把x=7z-2y代入x-y+z\x+y+z,得8z-3y/8z-y
4.把2z=y代入8z-3y/8z-y,得结果1/3
答案1/3
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联立方程组：4x-3y=6z x+2y=7z，解得：x=3z，y=2z
所以：(x-y+z)/(x+y+z)=(3z-2z+z)/(3z+2z+z)=2z/6z=1/3

因·4x-3y-6z=0,
x+2y-7z=0
所以4x-3y=6z
x+2y=7z，
解得：
x=3z
y=2z
所以：（x-y+z）/（x+y+z）=（3z-2z+z）/（3z+2z+z）=2z/6z=1/3