[2X+Y-Z=2 ; [X+2Y=5 ; [X-Y+2Z=-7

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)^2-(x-y+z)^2=? x,y,z为实数 且(y-z)^2+(x-y)^2+(z-x)^2=(y+z-2x)^2+(x+z-2y)^2+(x+y {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 x,y,z为实数且(y-z)平方+(x-y)平方+(z-x)平方=(y+z-2x)平方+(z+x-2y)平方+(x+y- 分解因式:f(x,y,z)=x^2(y-z)+y^2(z-x)+z^2(x-y) 解方程组2x+y-z=7 x+y+z =1 2x-y-z=5 已知2x+5y+4z=6.3x+y-7z=-4 求 x+2y+z 2x+5y+4z=0,3x+y-7z=0,则x+y-z=? 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z