Art of Problem Solving

2021 OIM Problems/Problem 5: Difference between revisions

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Created page with "== Problem == For a finite set <math>C</math> of integers, we define <math>S(C)</math> to be the sum of the elements of <math>C</math>. Find two nonempty sets <math>A</math>..."
 
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== Solution ==
== Solution ==
{{solution}}
The solution to the equation is <math>S(A)=491103</math> and <math>S(B)=1552128</math>; we can simply consider removing numbers to find the sets themselves, which just so happen to be
<cmath>A=\{x|x\in\mathbb{Z},x\in[1,1074]\cup[1076,1762]\}</cmath>
<cmath>B=\{x|x\in\mathbb{Z},x\in\{1075\}\cup[1763,2021]\}</cmath>
 
~ [https://artofproblemsolving.com/wiki/index.php/User:Eevee9406 eevee9406]


== See also ==
== See also ==
https://olcoma.ac.cr/internacional/oim-2021/examenes
https://olcoma.ac.cr/internacional/oim-2021/examenes

Latest revision as of 16:31, 15 April 2025

Problem

For a finite set $C$ of integers, we define $S(C)$ to be the sum of the elements of $C$. Find two nonempty sets $A$ and $B$, whose intersection is empty and whose union is the set ${1, 2, \cdots , 2021}$, such that the product $S(A)S(B)$ is a perfect square.

Solution

The solution to the equation is $S(A)=491103$ and $S(B)=1552128$; we can simply consider removing numbers to find the sets themselves, which just so happen to be \[A=\{x|x\in\mathbb{Z},x\in[1,1074]\cup[1076,1762]\}\] \[B=\{x|x\in\mathbb{Z},x\in\{1075\}\cup[1763,2021]\}\]

~ eevee9406

See also

https://olcoma.ac.cr/internacional/oim-2021/examenes