xy/(x+y)=-2 (x+y)/(xy)=-1/2,1/x +1/y =-1/2yz/(y+z)=4/3,(y+z)/(yz)=3/4,1/y +1/z =3/4 zx/(z+x)=-4/3,(z+x)/(zx)=-3/4 1/z +1/x=-3/4将以上三式相加,得：2(1/x+1/y+1/z)=-1/2+3/4-3/4(1/x+1/y+1/z)=-1/4所以：(xy...