Show that the transformation \(w=2z+1/z\) maps the unit circle conformally onto the
ellipse \[ \left (\frac {u}{3}\right )^2+v^2=1. \] Here \(w=u+iv\).
Find the Möbius transformation that takes the points \(z_1=0\), \(z_2=1\), \(z_3=-i\) into \(w_1=1\), \(w_2=0\), \(w_3=i\).