若x-y+z=0,2x-3y-4z=0,且xyz≠0,求(2x²+3y²+4z²）/（x²+3y²-2z²）的值

2x+z=10 x+y-z=4 3x-y-z=0 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 若x/2=y/3=z/4不等于0,求x+y+z/x+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 若4x-3y-6z=0,x+2y-7z=0,则x+y+z/3x-y+z=? 若(4x-3y-3z)^2+|x-3y-z|=0 且xyz不等于0 则4x+y-z/x+y+z 的值 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 {2x+y=10 {x-y+z=4 {3x-y-z=0 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 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,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 1.若3x-2y+z=2;3x+2y+5z=4,求x+22.若x-3y+z=0;3x-3y-4z=0,求x:y:z 若（z-x)的平方-4(x-y)(y-z)=0试确定x-2y+z若（z-x)^2-4(x-y)(y-z)=0试确定x-2y+z 三元一次方程x+y+z=0 4x+2y+z=3 9x+3y+z=6x+y+z=04x+2y+z=3 9x+3y+z=6 解方程 x+y+z=0 4x+2y+z=3 9x-3y+z=28解方程x+y+z=04x+2y+z=39x-3y+z=28 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 三元一次方程组题目x+y-z=11 y+z-x=5 x-y+z=1x+y=4 y+z=3 x+z=5若已知x-3y+2z=0 2x+3y-8z=0, 且xyz≠0,则x:y:z=