3x+2y+z=39 {2x+3y+z x+3y+3z

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) x/2=y/3=z/5 x+3y-z/x-3y+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=z/3,x+y+z ＝12,求2x+3y+4z是多少, 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 1.（x+y-z)+(x-y+z)-(x-y-z) 2.2x-(3x-2y+3)-(5y-2) 3道高数题,1,函数F(x,y,z)=(e^x) * y * (z^2) ,其中z=z(x,y)是由x+y+z+xyz= {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 如果,根号x-3+| y-2 |+z^2=2z-1 求 （x+z)^y x+2y=3 x+y+z=36 2x+y+z=15 2y=3z x-y=1 x+2y+z x-z=-1 2x+z-y=1 因式分解：25x y^2 z^2 (x+y-z)-30xyz(z-x-y)^2+5x y z^3 (z-x-y) 试证明(x+y-2z)³+(y+z-2x)³+(z+x-2y)³=3(x+y-2z)(y+