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RJLiberator
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Homework Statement
Find the bilinear transformation that maps the points z1=infinity, z2=i, z3=0 to the points w1=0, w2=i, w3=infinity.
Homework Equations
w=(az+b)/(cz+d)
The answer is -1/z
The Attempt at a Solution
We have:
infinity --> 0
i --> i
0 --> infinity
Since 0 goes to infinity, it means the denominator "is 0", so therefore d must be 0 in our relevant equation right off the bat.
If we take the limit as z--> infinity, we are supposed to get w=0, so 0=a/c in the limit and we see that a=0.
So now we are left with b/cz
and i-->
i=b/(ci) and we see that -c=b
But how do I prove here that c=1, and b=-1 instead of something else?
thanks.