x+2y-z=3 2x+y+3z=0 4x+z=-4

2x+z=10 x+y-z=4 3x-y-z=0 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 x+2y=3x+2z=4y+z 求x:y:z x+y/2=z+x/3=y+z/4 x+y+z=27 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z {2x+y=10 {x-y+z=4 {3x-y-z=0 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 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)=____. x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 x+y=2z=4,x-2y+z=-2,x+2y+3z=0 已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=? 已知x-2y+3z=0,x-3y+4z=0,则x:y:z= X+y-z=6;x-3y+2z=0;3x+2y-z=4