Difference between revisions of "2024 IMO Problems/Problem 6"

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==Video Solution 2==
 
==Video Solution 2==
 
https://youtu.be/ydnmT8B68Co
 
https://youtu.be/ydnmT8B68Co
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==Video Solution 3,中文版,subtitle in English==
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https://youtu.be/2V1ogM-VBq4
  
 
==See Also==
 
==See Also==
  
 
{{IMO box|year=2024|num-b=5|after=Last Problem}}
 
{{IMO box|year=2024|num-b=5|after=Last Problem}}

Latest revision as of 21:53, 14 November 2024

Let $\mathbb{Q}$ be the set of rational numbers. A function $f: \mathbb{Q} \to \mathbb{Q}$ is called $\emph{aquaesulian}$ if the following property holds: for every $x,y \in \mathbb{Q}$, \[f(x+f(y)) = f(x) + y \quad \text{or} \quad f(f(x)+y) = x + f(y).\]Show that there exists an integer $c$ such that for any aquaesulian function $f$ there are at most $c$ different rational numbers of the form $f(r) + f(-r)$ for some rational number $r$, and find the smallest possible value of $c$.

Video Solution

https://youtu.be/7h3gJfWnDoc

Video Solution 2

https://youtu.be/ydnmT8B68Co

Video Solution 3,中文版,subtitle in English

https://youtu.be/2V1ogM-VBq4

See Also

2024 IMO (Problems) • Resources
Preceded by
Problem 5
1 2 3 4 5 6 Followed by
Last Problem
All IMO Problems and Solutions