已知x+y-7z=0,且x-2y+5z=0（xyz≠0）,求x+2y-z/-2x+y+12z的值

已知x.y.z满足x-2y+z=0且7x+4y-5z=0,求x:y:z的值 已知x,y,z满足方程组x-2y+z=0 7x+4y-5z=0,且z不等于0,2x²-3y²+z²/y²-2z²的值为? 已知 (x+y-z)/z=(x-y+z)/y=(y+z-x)/x,且xyz≠0,求代数式 ((x+y)(y+z)(x+z))/xyz 已知xyz不等于0,且x+2y-z=0,7x-y-z=0,求x+y+z/2x-y-z的值. 已知5分之X+Y=6分之Y+Z=7分之x+z,且X,Y,Z都不等于0,求X:Y:Z的值 已知:(x+y)/5=(y+z)/6=(x+z)/7,且x,y,z不全为0,求x：y：z 已知4x-3y-6z=0,x+2y-7z=0,且x,y,z≠0,求2x+3y+6z/x+5y+5z的值. 已知xyz不等于0,且{x+3y+5z=0 x2+3y+z=0,则x.x+y.y-2z.2z/3x.3x+2y.2y+z.z=? 已知xy/5=y+z/6=z+x/7,且xyz不等于0,求x:y:z 已知：(x+y-z)/z=(x-y+z)/y+(y+z-x)/x,且xyz≠0,求代数式[(x+y)(y+z)(x+z)]/xyz的值已知：(x+y-z)/z=(x-y+z)/y=(y+z-x)/x,且xyz≠0,求代数式[(x+y)(y+z)(x+z)]/xyz的值 题目中写错个等号，汗... 已知3x-2y-5z=0,x+2y+-7z=0且xyz ≠0求(x*-2y*+z)/yz 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. 已知方程组{4x-3y-6z=0 x+2y-7z=0 且z≠0,则（x+y+3z）÷（4x-y-5z）=?结果和思路! 已知方程组{X+Y-7Z=0(1)3X-2Y-Z=0(2)且Z不等于0求X:Y:Z 快已知方程组；x+y-7z=0 3x-2y-z=0,且z≠0,求x：y：z加减消元法 已知方程组{x+y-7z=0,3x-2y-z=0,且z≠0,求X:Y:Z 已知x,y,z,满足方程组x-2y+z=0,7x+4y-5z=0