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MathNet 2023-part-05 — 191 problems (EN–VI) Question 53

Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)

Question 53

Let $n \in \mathbb{N}$, $n \ge 2$. Determine all $z \in \mathbb{C}$ such that:
$$
|z^{n+1} - z^n| \ge |z^{n+1} - 1| + |z^{n+1} - z|
$$