Solution

ID: past-exam-of-the-mathematics-course-of-the-year-2-of-the-natural-sciences-course-of-the-university-of-cambridge/2018/paper-2/4/a/solution

A sufficient contour setting for both results is a positively oriented, simple, closed, piecewise smooth contour , with the function holomorphic on an open neighbourhood of and its entire interior. The Cauchy integral theorem then states
If is strictly inside , the Cauchy integral formula states
The contour must not pass through . Positive orientation means anticlockwise; reversing it reverses the sign of the contour integral. The holomorphy assumption throughout the interior excludes hidden singularities there.

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