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2009 Ukraine National Mathematical Olympiad
2
Find all Z → Z functions - [UKRMO 2009 Grade 11]
Find all Z → Z functions - [UKRMO 2009 Grade 11]
Source:
January 23, 2011
function
absolute value
algebra proposed
algebra
Problem Statement
Find all functions
f
:
Z
→
Z
f : \mathbb Z \to \mathbb Z
f
:
Z
→
Z
such that
f
(
n
∣
m
∣
)
+
f
(
n
(
∣
m
∣
+
2
)
)
=
2
f
(
n
(
∣
m
∣
+
1
)
)
∀
m
,
n
∈
Z
.
f (n |m|) + f (n(|m| +2)) = 2f (n(|m| +1)) \qquad \forall m,n \in \mathbb Z.
f
(
n
∣
m
∣
)
+
f
(
n
(
∣
m
∣
+
2
))
=
2
f
(
n
(
∣
m
∣
+
1
))
∀
m
,
n
∈
Z
.
Note.
∣
x
∣
|x|
∣
x
∣
denotes the absolute value of the integer
x
.
x.
x
.
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