|x-2|+|y-3|+|z-4|=0 计算,求出x+y-z的值!写在纸上

2x+z=10 x+y-z=4 3x-y-z=0 {2x+y=10 {x-y+z=4 {3x-y-z=0 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)=____. 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>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=2z=4,x-2y+z=-2,x+2y+3z=0 已知2x-y-z=0,3x+4y-2z=0,则x：y：z=? 已知x+4y-3z=0,4x-5y+2z=0,则x：y：z X+y-z=6;x-3y+2z=0;3x+2y-z=4 3X+Y+Z=0,2X-Y+3Z=1,X+2Y-Z=4 2x+3y+z=0 3x+y-4z=11 x+y+z=-3 2x+3y+z=0 3x+y-4z=11 x+y+z=-3 x+2y-4z=0,3x+y-z=0,则x:y:z=?：： x+2y-4z=0 3x+y-z=0,则x:y:z= 5x+4y+z=0 3x+y-4z=13 x+y+z=—2