已知,xyz=0,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1）值?
问题描述：
已知,xyz=0,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1）值?
答
同学,xyz=1吧?这样的话,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)=(...