 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2025/ia/paper-3/6d/d/i/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

For

g \in G

and

x \in ϕ^{- 1} (N)

ϕ (gx g^{- 1}) = ϕ (g) ϕ (x) ϕ (g)^{- 1} \in N,

so the preimage is normal.

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