结果等于：1原式=x/(xy+x+xyz)＋y/(yz+y+xyz)＋z/(xz+z+xyz)=1/(y+1+yz)+1/(z+1+xz)+1/(x+1+xy)=xyz/(y+xyz+yz)+1/(z+1+xz)+1/(x+1+xy)=xz/(1+xz+z)+1/(z+1+xz)+1/(x+1+xy)=(xz+1)/(z+1+xz)+1/(x+1+xy)=(xz+xyz)/(z+...