x-5y-3z=0 y+z-3x=3 x+y+3z=14 y+4z=3 z+x-3y=5 2x+y+z=7 2x-z=1

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) {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 2x+5y+4z=0,3x+y-7z=0,则x+y-z=? 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 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? 已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5 已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=? 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z