x-2y+z=0；3x+y-2z=0；7x+6y+7z=100； 解这个三元一次方程组,

证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,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 2x+z=10 x+y-z=4 3x-y-z=0 (1)X+Y=15,Y+Z=-6,Z+X=7.(2)X+Y=-14,Y+Z=-7,Z+X=9.(3)X+Y=0,Y+Z=-1,Z+X=-1. 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 x+y+z=0,3x-2y-2z=5,y-z=2x-7 X-Y-Z=0 X+Y-3Z=4 2X-5Y+7Z=21 解三元一次方程：x+y-z=0,2x+y+z=7,x-3y+z=8 解方程组x+y-z=0,2x+y+z=7,x-3y+z=8 1.{x:y:z=3:4:5 2x+3y-5z=-142.{x-y-z=-1 3x+5y+7z=11 4x-y+2z=-13.{x+y=1 x+z=0 2x+y+2z=44.{x-y+z=-3 2x-y-z=-2 -3x+y+z=-15.{x-y+z=-3 3x+y-4z=6 2x+y-z=36.{x-2y+5z=16 2x+y-5z=7 2x-y+z=38 已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 若4x-3y-6z=0,x+2y-7z=0,则x+y+z/3x-y+z=? 已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________ 已知4x-3y+6z=0 x+2y-7z=0 则x-y+z/x+y-z=?