Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2008/ia/paper-3/7e/ii/solution

The assertion is false. Let and . Their relations are
Moving each inversion to the right reduces every word to with or . Thus the subgroup generated by complex scalings and reciprocal inversion consists only of and . Of these, only the first form fixes zero.
The Möbius transformation
fixes zero but is not a scaling: it sends infinity to instead of infinity. It therefore cannot belong to the subgroup generated by scalings and reciprocal inversion.

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