5x+y+z=1 2x-y+2z=1 x+5y-z=4

{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? 已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. {5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=- 已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z. x/2=y/3=z/5 x+3y-z/x-3y+z x+2y+z=1 x+y+2z=2 2x+y+z=5 x+y+z=2 x-3y+2z=1 2x+2y+z+5 要具体步骤.. 解方程组2x+y-z=7 x+y+z =1 2x-y-z=5 3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5 已知 x,y,z都是正实数,且 x+y+z=xyz 证明 (y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1 解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y