x+y+z=2y=3z(y≠0),求（xy+yz+zx）÷（x²+y²+z²）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 分式加减法：已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z 已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z的步骤 已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z的步骤 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 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. 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 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 x+2y=3x+2z=4y+z 求x:y:z 已知方程组4x-3y-2z=0,x-3y+z=0,z≠0求x/z,y/z的值 若xyz≠0且4(x/z)-5(y/z)=-2,(x/z)+4(y/z)=3,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... 已知方程组2x-3y-4z=0和x+y+z=0,并且z≠0,求x：y与y：z 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 已知z、y、z同时满足x+3y-5z=0,2x-y-3z=0,求x:y:z 已知4x-3y-6z=0,x+2y-7z=0,xyz≠0,求x-y+2z/x+y-zx-y+2z分之x+y-z x分之y+z=y分之z+x=z分之x+y(x+y+z不等于0）,求x+y+z分之x+y-z