Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2008/iii/paper-12/1/a/solution

The assertion is true. The assumed finite multiplicity means that is not identically zero and has an isolated zero of order at . Choose so that and has no other zeros in this closed disc. On its boundary,
The joint holomorphy established above gives uniformly on that circle as . For sufficiently small , therefore, . By Rouché's theorem, has exactly zeros in , counted with multiplicity. In particular it has at least one zero in . This preserves the total local zero count, without asserting that the zeros remain together.

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