-x+2y+3z=12 2x-2y+5z=13 3x+2y+z=10

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) x/2=y/3=z/5 x+3y-z/x-3y+z x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5 {2x+3y-4z=-5 x+y+z=6 x-y+3z=10 {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X 1.x+y+z=21,x-y=1,2x+z-y=13.2.3x+2y+z=13,x+y+2z=7 ,2z+3y-z=12 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 3x+2y+z=13 x+y+2z=7 2x+3y-z=12 x=?y=?z=?