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Site Support Tech support and questions about AoPS classes and materials
Tech support and questions about AoPS classes and materials
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Integer representation
RL_parkgong_0106   1
N 23 minutes ago by Jackson0423
Source: Own
Show that for any positive integer $n$, there exists some positive integer $k$ that makes the following equation have no integer root $(x_1, x_2, x_3, \dots, x_n)$.

$$x_1^{2^1}+x_2^{2^2}+x_3^{2^3}+\dots+x_n^{2^n}=k$$
1 reply
RL_parkgong_0106
3 hours ago
Jackson0423
23 minutes ago
Equations
Jackson0423   0
28 minutes ago
Solve the system of equations
\[
\begin{cases}
x - y z = 1,\\[2pt]
y - z x = 2,\\[2pt]
z - x y = 4.
\end{cases}
\]
0 replies
Jackson0423
28 minutes ago
0 replies
Factor of P(x)
Brut3Forc3   19
N 29 minutes ago by xytunghoanh
Source: 1976 USAMO Problem 5
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)$.
19 replies
Brut3Forc3
Apr 4, 2010
xytunghoanh
29 minutes ago
2^x+3^x = yx^2
truongphatt2668   1
N 31 minutes ago by Jackson0423
Prove that the following equation has infinite integer solutions:
$$2^x+3^x = yx^2$$
1 reply
truongphatt2668
an hour ago
Jackson0423
31 minutes ago
FE solution too simple?
Yiyj1   7
N an hour ago by ariopro1387
Source: 101 Algebra Problems from the AMSP
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?
7 replies
1 viewing
Yiyj1
Apr 9, 2025
ariopro1387
an hour ago
A cyclic inequality
KhuongTrang   2
N an hour ago by NguyenVanDucThang
Source: own-CRUX
IMAGE
https://cms.math.ca/.../uploads/2025/04/Wholeissue_51_4.pdf
2 replies
KhuongTrang
Yesterday at 4:18 PM
NguyenVanDucThang
an hour ago
Iran second round 2025-q1
mohsen   3
N an hour ago by Parsia--
Find all positive integers n>2 such that sum of n and any of its prime divisors is a perfect square.
3 replies
mohsen
Apr 19, 2025
Parsia--
an hour ago
hard problem
Cobedangiu   6
N an hour ago by Jackson0423
Let $x,y,z>0$ and $xy+yz+zx=3$ : Prove that :
$\sum  \ \frac{x}{y+z}\ge\sum  \frac{1}{\sqrt{x+3}}$
6 replies
Cobedangiu
Apr 2, 2025
Jackson0423
an hour ago
2016 Kmo Final round
Jackson0423   0
an hour ago
Source: 2016 FKMO P4
Let \(x,y,z\in\mathbb R\) with \(x^{2}+y^{2}+z^{2}=1\).
Find the maximum value of
\[
(x^{2}-yz)(y^{2}-zx)(z^{2}-xy).
\]
0 replies
Jackson0423
an hour ago
0 replies
Factor sums of integers
Aopamy   1
N an hour ago by BR1F1SZ
Let $n$ be a positive integer. A positive integer $k$ is called a benefactor of $n$ if the positive divisors of $k$ can be partitioned into two sets $A$ and $B$ such that $n$ is equal to the sum of elements in $A$ minus the sum of the elements in $B$. Note that $A$ or $B$ could be empty, and that the sum of the elements of the empty set is $0$.

For example, $15$ is a benefactor of $18$ because $1+5+15-3=18$.

Show that every positive integer $n$ has at least $2023$ benefactors.
1 reply
Aopamy
Feb 23, 2023
BR1F1SZ
an hour ago
a