Equations

by Jackson0423, Apr 22, 2025, 4:36 PM

Solve the system of equations
\[
\begin{cases}
x - y z = 1,\\[2pt]
y - z x = 2,\\[2pt]
z - x y = 4.
\end{cases}
\]

2^x+3^x = yx^2

by truongphatt2668, Apr 22, 2025, 3:38 PM

Prove that the following equation has infinite integer solutions:
$$2^x+3^x = yx^2$$

Integer representation

by RL_parkgong_0106, Apr 22, 2025, 2:23 PM

Show that for any positive integer $n$, there exists some positive integer $k$ that makes the following equation have no integer root $(x_1, x_2, x_3, \dots, x_n)$.

$$x_1^{2^1}+x_2^{2^2}+x_3^{2^3}+\dots+x_n^{2^n}=k$$

A cyclic inequality

by KhuongTrang, Apr 21, 2025, 4:18 PM

https://scontent.fsgn8-3.fna.fbcdn.net/v/t39.30808-6/492231047_688189297700214_244542319935452144_n.jpg?_nc_cat=100&ccb=1-7&_nc_sid=127cfc&_nc_ohc=xQijXmYebS4Q7kNvwFGnEsJ&_nc_oc=AdnkURNB_TMHGDtMopGwGHIze5ttpMfPlG6_IvyiEtuBvsrjxmHu2ER5OMaRWyfSq1oAwajVe1_upssAjnhpMkCO&_nc_zt=23&_nc_ht=scontent.fsgn8-3.fna&_nc_gid=NwcFC-jSTnopA34ZcTHl0Q&oh=00_AfEX7I6TDrNddWcG3dW1-eKfIW1nhr5kYROU6TEFmN56kg&oe=680C389C
https://cms.math.ca/.../uploads/2025/04/Wholeissue_51_4.pdf

Iran second round 2025-q1

by mohsen, Apr 19, 2025, 10:21 AM

Find all positive integers n>2 such that sum of n and any of its prime divisors is a perfect square.

Arrangement of integers in a row with gcd

by egxa, Apr 18, 2025, 5:09 PM

Let \( n \) be a natural number. The numbers \( 1, 2, \ldots, n \) are written in a row in some order. For each pair of adjacent numbers, their greatest common divisor (GCD) is calculated and written on a sheet. What is the maximum possible number of distinct values among the \( n - 1 \) GCDs obtained?
This post has been edited 1 time. Last edited by egxa, Apr 18, 2025, 5:18 PM

FE solution too simple?

by Yiyj1, Apr 9, 2025, 3:26 AM

Find all functions $f: \mathbb{R} \rightarrow \mathbb{R}$ such that the equality $$f(f(x)+y) = f(x^2-y)+4f(x)y$$holds for all pairs of real numbers $(x,y)$.

My solution

I feel like my solution is too simple. Is there something I did wrong or something I missed?

Factor of P(x)

by Brut3Forc3, Apr 4, 2010, 2:45 AM

If $ P(x),Q(x),R(x)$, and $ S(x)$ are all polynomials such that \[ P(x^5)+xQ(x^5)+x^2R(x^5)=(x^4+x^3+x^2+x+1)S(x),\] prove that $ x-1$ is a factor of $ P(x)$.

Estonian Math Competitions 2005/2006

by STARS, Jul 30, 2008, 1:17 AM

A $ 9 \times 9$ square is divided into unit squares. Is it possible to fill each unit square with a number $ 1, 2,..., 9$ in such a way that, whenever one places the tile so that it fully covers nine unit squares, the tile will cover nine different numbers?

Sum of whose elements is divisible by p

by nntrkien, Aug 8, 2004, 1:29 AM

Let $ p$ be an odd prime number. How many $ p$-element subsets $ A$ of $ \{1,2,\dots,2p\}$ are there, the sum of whose elements is divisible by $ p$?

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