3x-y+2z=3 2x+y-3z=11 x+y+z=12

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, x/2=y/3=z/5 x+3y-z/x-3y+z 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 3x-y+z=3 2x+y-3z=11 x+y+z=12 解方程 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.x+y=16,y+z=12,z+x=102.3x-y+z=4,2x+3y-z=12,x+y+z=63.x+y+z=6 x+2y+3z=14 2x+y+z=7 3x+y+2z=11 3x+2y+z=9,x+y+2z=0,2x+3y-z=11 2x+3y+z=11,3x+y-z=2,x+y+z=6求解 x+2y+4z=17 2x+y+z=7 3x+y+2z=11 解方程组{2x+3y+z=11,x+y+z=0,3x-y+z=-2.