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National and Regional Contests
Moldova Contests
Moldova Team Selection Test
2001 Moldova Team Selection Test
9
show that $|z|<1$
show that $|z|<1$
Source: Moldova TST 2001
August 7, 2023
complex numbers
Problem Statement
If
z
∈
C
z\in\mathbb{C}
z
∈
C
is a solution of the equation
x
n
+
a
1
x
n
−
1
+
a
2
x
n
−
2
+
…
+
a
n
=
0
x^n+a_1x^{n-1}+a_2x^{n-2}+\ldots+a_n=0
x
n
+
a
1
x
n
−
1
+
a
2
x
n
−
2
+
…
+
a
n
=
0
with real coefficients
0
<
a
n
≤
a
n
−
1
≤
…
≤
a
1
<
1
0<a_n\leq a_{n-1}\leq\ldots\leq a_1<1
0
<
a
n
≤
a
n
−
1
≤
…
≤
a
1
<
1
, show that
∣
z
∣
<
1
|z|<1
∣
z
∣
<
1
.
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