z=1/w=1/(u+iv)=(u-iv)/(u^2+v^2)z=x+iyx=u/(u^2+v^2),y=-v/(u^2+v^2),(u/(u^2+v^2))^2+(-v/(u^2+v^2)-1)^2=4所求曲线方程为：u^2+(u^2+v^2+v)^2=4(u^2+v^2)^2
