1/x+1/y=1/6 1/y+1/z=1/9 1/z+1/x=1/15 求xyz/xy+yz+xz的值

已知xyz=1,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1)的值 x+y+z=1,x,y,z都是正数,求xy+yz+xz-3xyz的最大值和最小值 已知,xyz=0,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1）值? XYZ-XY-XZ+X-YZ+Y+Z-1 xyz-xy-xz+x-yz+y+z-1因式分解 设x,y,z∈R+,xy+yz+xz=1,证明不等式:(xy)^2/z+(xz)^2/y+(yz)^2/x+6xyz≥x X,Y,Z为实数,且XY/X+Y=1/3,YZ/Y+Z=1/4,XZ/X+Z=1/5,求XYZ/XY+YZ+XZ的值 1/x+1/y=1/2,1/y+1/z=1/3,1/x+1/z=1/6,求xyz/(xy+yz+xz)的值 设x+y+z=3.求代数式[3[xyz-xy-xz-yz]+6]/[[x-1]^3+[y-1]^3+[z-1]^3]的值 已知xyz=1,试求(1/xy+x+1)+(1/yz+y+1)+(1/xz+z+1)的值 急用,等答案.若xyz=1,求 (x/xy+x+1)+(y/yz+y+1)+(z/xz+z+1) 的值 x/(xy+x＋1)＋y/(yz+y+1)＋z/(xz+z+1)=?其中 xyz＝1