已知xyz=1,x+y+z=2,x^3+y^3+z^3=3,求1/xy+z-1+1/yz+x-1+1/zx+y-1

已知实数xyz满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3求x+y+z的值 已知x,y,z都是正数,且xyz=1,求证：x^2/(y+z)+y^2/(x+z)+z^2/(x+y)≥3/2 已知x,y,z>0,xyz(x+y+z)=1,求证（x+y）(x+z)>=2 已知x^2+y^2+z^2=1,求证x+y+z-2xyz 先化简再求值3xyz+2(x^2y+y^2z-xyz)-xyz+2z^2x x=1 y= -1 z=2 先化简,再求值：3xyz+2(x²y+y²z-xyz)-xyz+2z²x,其中x=1、y=-1、z=2; 已知x+y+z=0求证x*x*x+y*y*y+z*z*z=3xyz 已知xyz≥0,x+y+z=1,化简x（2y-z）/(1+x+3y)+y(2z-x) /(1+y+3z) +z(2x-y)/(1+z+3x) 已知x:y:z=3:2:1,且x+y+z=12,则xyz=? 已知x:y:z=2:3:4,且x+y+z=1/12,求xyz的值 已知xyz满足|3x-2y+z|+|2x+y+2z|=0（xyz不等于o）求x+y除以z 已知xyz适合关系式√3x+y-z-2+√2x+y-z=√x+y-2011+2011-x-y,试求xyz的值 3x^2y-[2x^2y-(2xyz-x^2z)-4x^2z]-xyz ,其中x=-2,y=-3,z=1 X^2Y-[-X^2Y+(XYZ-X^2Z)+XYZ]-X^2Z,其中x=-1,y=-2,z=1/3 3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz,其中x=-2 y=-3 z=1 x+y+z+2=xyz,x,y,z.为正实数,证明：xyz(x-1)(y-1)(z-1) 已知 (x+y-z)/z=(x-y+z)/y=(y+z-x)/x,且xyz≠0,求代数式 ((x+y)(y+z)(x+z))/xyz 已知x+y+z=3,xy+yz+xz=-1,xyz=2,求x^2y^2+y^2z^2+x^2z^2