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Serbia Team Selection Test
2022 Serbia Team Selection Test
P1
P1
Part of
2022 Serbia Team Selection Test
Problems
(1)
Polynomials
Source: Serbia TST 2022, Problem 1
5/31/2023
For a non-constant polynomial
P
(
x
)
=
a
n
x
n
+
a
n
−
1
x
n
−
1
+
…
+
a
1
x
+
a
0
∈
R
[
x
]
,
a
n
≠
0
,
n
∈
N
P(x)=a_{n} x^{n}+a_{n-1} x^{n-1}+\ldots+a_{1} x+a_{0} \in \mathbb{R}[x], a_{n} \neq 0, n \in \mathbb{N}
P
(
x
)
=
a
n
x
n
+
a
n
−
1
x
n
−
1
+
…
+
a
1
x
+
a
0
∈
R
[
x
]
,
a
n
=
0
,
n
∈
N
, we say that
P
P
P
is symmetric if
a
k
=
a
n
−
k
a_{k}=a_{n-k}
a
k
=
a
n
−
k
for every
k
=
0
,
1
,
…
,
⌈
n
2
⌉
k=0,1, \ldots,\left\lceil\frac{n}{2}\right\rceil
k
=
0
,
1
,
…
,
⌈
2
n
⌉
. We define the weight of a non-constant polynomial
P
∈
R
[
x
]
P \in \mathbb{R}[x]
P
∈
R
[
x
]
, denoted by
t
(
P
)
t(P)
t
(
P
)
, as the multiplicity of its zero with the highest multiplicity.a) Prove that there exist non-constant, monic, pairwise distinct polynomials
P
1
,
P
2
,
…
,
P
2021
∈
R
[
x
]
P_{1}, P_{2}, \ldots, P_{2021} \in \mathbb{R}[x]
P
1
,
P
2
,
…
,
P
2021
∈
R
[
x
]
, none of which is symmetric, such that the product of any two (distinct) polynomials is symmetric.b) What is the smallest possible value of
t
(
P
1
⋅
P
2
⋅
…
⋅
P
2021
)
t\left(P_{1} \cdot P_{2} \cdot \ldots \cdot P_{2021}\right)
t
(
P
1
⋅
P
2
⋅
…
⋅
P
2021
)
, if
P
1
,
P
2
,
…
,
P
2021
∈
R
[
x
]
P_{1}, P_{2}, \ldots, P_{2021} \in \mathbb{R}[x]
P
1
,
P
2
,
…
,
P
2021
∈
R
[
x
]
are non-constant, monic, pairwise distinct polynomials, none of which is symmetric, and the product of any two (distinct) polynomials is symmetric?
polynomial
algebra