已知x+y+z不等于0, x[(1/y)+(1/z)]+y[(1/z)+(1/x)]+z[(1/x)+(1/y)]+3=0 求证：xy+yz+zx=0

已知:(x+y)/z=(x+z)/y=(z+y)/x,且xyz不等于0,则分式(x+y)(x+z)(z+x)/xyz的值为? 已知x,y,z满足{4x-3y-3z=0,x-3y+z=0.（x不等于0,y不等于0,z不等于0）求x/z和y/z的值 已知x+y-7z=0 x-2y+5z=0(xyz不等于0）,求x+2y-z/y-2x+12z 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. 已知方程组4x-3y-3z=0 ,x-3y+z=0 (x,y,z,不等于0) 求x:y:z 已知方程组4x-y+3z=0 2x+y+6z=0且xyz不等于0,则x/y+y/z+z/x是多少 已知2x-y-3z=0 x-2y+z=0,且x、y、z都不等于0,求x：y：z 已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值 已知4x-3y-3z= 0,x-3y+z=0中x,y,z不等于0,则x:y:z为? 已知方程组{2x-3y+z=0 且x*y*z不等于0 求 x：y：z {3x-2y-6z=0 已知x+y+z=0,xyz不等于0化简:(x^2/y+z)+(y^2/x+z)+(z^2/x+y) 已知（x+y)(y+z)(z+x)=0,xyz不等于0 求证：1/x+1/y+1/z=1/(x+y+z) 已知x+y+z不等于0,若2y+z/x=2x+y/z=2z+x/y=k,则k= 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/2=y/3=z/4,且x+y+z不等于0,求2x+3y-4z/x+y+z的值 已知x/2=y/3=z/4,且x+y+z不等于0,求2x+3y-4z/x+y+z的值 已知4x-3y-3z=0,① x-3y+z=0,②并且z不等于0,求x：z与y：z 已知xy/5=y+z/6=z+x/7,且xyz不等于0,求x:y:z