Conformal Mappings - Mobius Transformations

Hi Guys, Any help with this greatly appreciated:
Attachment 3895
Note: Equation for part (ii) is "every line or circle has an equation of the form
a(x^2+y^2)+bx+cy+d=0, where a,b,c,d are subset R and b^2+c^2>4ad

Thank you
The Moolimuncha

...The Moolimuncha? :p:D:eek:



Anyway... f maps the circle C into either a circle or a line. One simple way to do this, is to find three points on C and their respective values through f. If these values are collinear, then f(C) is this line; If not, f(C) is a circle, whose equation can be found from those three points. :o

Thanks Rebesques

But I'm still confused. Can you expand please?

Cheers
Moolimuncha