Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2008/ia/paper-4/6d/c/solution

The greatest common divisor is
since and are coprime integers. Part (b) therefore gives distinct th powers in the nonzero multiplicative group of a finite field . If “powers mod ” includes all residue classes, the additional value gives values including zero. The distinction is relevant because part (b) explicitly works in the nonzero group.

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