6X^2-7xy-3y^2-xz+7yz-2z^2因式分解,

(2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ) 因式分解x^2-xy+xz-yz 已知2/x=3/y=7/z,求xy+xz+yz/x^2+y^2+z^2 求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ) 因式分解x^2+y^2+z^2+2xy+2yz+2xz-2x-2y-2z+1 化简(2x-y-z/x^2-xy-xz+yz)+(2y-x-z/y^2-xy-yz+xz)+(2x-x-y/z^2-xz 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 一元二次方程的应用 已知xy=xz+3,yz=xy+xz-7（x,y,z均为正整数）,求2（xy+yz+xz）的值. 已知x+y+z=5,xy+yz+xz=7,则x^2+y^2+z^2等于? x+3y+7z=0 2x+5y+11z=0,求(x^2+y^2+z^2)/(xy+2yz+3xz) 解方程组（x+y)/xy=5/6,(y+z)/yz=-2/3,2(x+3)+xz=0 xy／x+y＝1,yz／y＋z＝2,xz／x＋z＝3求x,y