(x+y-xy)/(x+y+2xy)=(y+z-2yz)/(y+z+3yz)=(z+x-3zx)/(z+x+4zx),且2/x=3/y-1/z,则xyz=?
问题描述：
(x+y-xy)/(x+y+2xy)=(y+z-2yz)/(y+z+3yz)=(z+x-3zx)/(z+x+4zx),且2/x=3/y-1/z,则xyz=?
看清楚是2/x=3/y-1/z
答
(x+y-xy)/(x+y+2xy) （上下同除以xy)=(1/x+1/y-1)/(1/x+1/y+2)=(2/x+2/y-2)/(2/x+2/y+4)=(5/y-1/z-2)/(5/y-1/z+4)=1-6/(5/y-1/z+4);同理(y+z-2yz)/(y+z+3yz)=(1/y+1/z-2)/(1/y+1/z+3)=1-5/(1/y+1/z+3);(z+x-3zx)/(z+...