Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2025/ia/paper-4/7d/b/solution

An element of the left side is for some with , exactly an element of . The second equality need not hold, even for a surjection: map to a singleton and take , . Then the image of the intersection is empty but the intersection of the images is not.

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