1.x - 5y -3z =3 2.4x+9y=12 3.3x-y+2z=3

x/2=y/3=z/5 x+3y-z/x-3y+z 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 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=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 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 1.x+y+z=30,3x+y-z=50,x,y,z为非负数,求5x+4y+2z取值范围. (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 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 {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 三元一次方程组x-2y=-9 3x-y+z=4 y=2x-7 y-z=3 2x+3y-z=12 5x+3y+2z=2 2 若x,y,z,满足3x+2y+z=5,2x+y-3z=1.y是非负数.求z的取值范围