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District Olympiad
2023 District Olympiad
P3
Complex number inequality
Complex number inequality
Source: Romanian District Olympiad 2023 10.3
March 11, 2023
complex numbers
inequalities
Problem Statement
Let
n
⩾
2
n\geqslant 2
n
⩾
2
be an integer. Determine all complex numbers
z
z{}
z
which satisfy
∣
z
n
+
1
−
z
n
∣
⩾
∣
z
n
+
1
−
1
∣
+
∣
z
n
+
1
−
z
∣
.
|z^{n+1}-z^n|\geqslant|z^{n+1}-1|+|z^{n+1}-z|.
∣
z
n
+
1
−
z
n
∣
⩾
∣
z
n
+
1
−
1∣
+
∣
z
n
+
1
−
z
∣.
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