若x+y+z>0,xy+xz+yz>0 xyz>0,求证x>0,y>0,z>0

若x+y+z>0,xy+xz+yz>0 xyz>0,求证x>0,y>0,z>0 (2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ) 若实数xyz满足(x-2y+z)^2+4(x-y)(y-z)=0 A xy-yz=0 B xy+yz=0 C xy-xz=0 D xy+xz=0 已知x2+y2+z2-xy-yz-xz=0,求证x=y=z -x=3,/y/=4,z+3=0,求xy+yz+xz的值 若x,y,z>0 则根号(x^2+y^2+xy)+根号(y^2+z^2=yz)>根号(x^2+z^2+xz)是求证题 化简(2x-y-z/x^2-xy-xz+yz)+(2y-x-z/y^2-xy-yz+xz)+(2x-x-y/z^2-xz-yz+xy) 已知x>0,y>0,z>0,求证：：（x+y+z）^3>=3(xy+yz+xz) 已知,xyz=0,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1）值? 已知x²+y²+z²-xy-xz-yz=0判断x、y、z的关系 已知x+y+z=1,xy+yz+xz=0,求x^2+y^2+z^2的值. X+y+z=1 xy+yz+xz=0 x^2+y^2+z^2=? 若xyz+xy+yz+xz+x+y+z=2008,则x+y+z=多少, 已知X＞Y＞Z,且X+Y+Z=0,则下列不等式中恒成立的是A,XY＞YZ B,XZ＞YZ　　C,XY＞XZ　　　D,X｜Y｜＞Z｜Y｜ 求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ) 已知x>0,y>0,z>0,证明x^3/(x+y)+y^3/(y+z)+z^3/(z+x)≥(xy+xz+yz)/2 xyz-xy-xz+x-yz+y+z-1因式分解 还是因式分解 xyz-xy-xz+x-yz+y+z-1