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k a May Highlights and 2025 AoPS Online Class Information
jlacosta   0
May 1, 2025
May is an exciting month! National MATHCOUNTS is the second week of May in Washington D.C. and our Founder, Richard Rusczyk will be presenting a seminar, Preparing Strong Math Students for College and Careers, on May 11th.

Are you interested in working towards MATHCOUNTS and don’t know where to start? We have you covered! If you have taken Prealgebra, then you are ready for MATHCOUNTS/AMC 8 Basics. Already aiming for State or National MATHCOUNTS and harder AMC 8 problems? Then our MATHCOUNTS/AMC 8 Advanced course is for you.

Summer camps are starting next month at the Virtual Campus in math and language arts that are 2 - to 4 - weeks in duration. Spaces are still available - don’t miss your chance to have an enriching summer experience. There are middle and high school competition math camps as well as Math Beasts camps that review key topics coupled with fun explorations covering areas such as graph theory (Math Beasts Camp 6), cryptography (Math Beasts Camp 7-8), and topology (Math Beasts Camp 8-9)!

Be sure to mark your calendars for the following upcoming events:
[list][*]May 9th, 4:30pm PT/7:30pm ET, Casework 2: Overwhelming Evidence — A Text Adventure, a game where participants will work together to navigate the map, solve puzzles, and win! All are welcome.
[*]May 19th, 4:30pm PT/7:30pm ET, What's Next After Beast Academy?, designed for students finishing Beast Academy and ready for Prealgebra 1.
[*]May 20th, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 1 Math Jam, Problems 1 to 4, join the Canada/USA Mathcamp staff for this exciting Math Jam, where they discuss solutions to Problems 1 to 4 of the 2025 Mathcamp Qualifying Quiz!
[*]May 21st, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 2 Math Jam, Problems 5 and 6, Canada/USA Mathcamp staff will discuss solutions to Problems 5 and 6 of the 2025 Mathcamp Qualifying Quiz![/list]
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All classes run 7:30pm-8:45pm ET/4:30pm - 5:45pm PT unless otherwise noted.

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0 replies
jlacosta
May 1, 2025
0 replies
k i Adding contests to the Contest Collections
dcouchman   1
N Apr 5, 2023 by v_Enhance
Want to help AoPS remain a valuable Olympiad resource? Help us add contests to AoPS's Contest Collections.

Find instructions and a list of contests to add here: https://artofproblemsolving.com/community/c40244h1064480_contests_to_add
1 reply
dcouchman
Sep 9, 2019
v_Enhance
Apr 5, 2023
k i Zero tolerance
ZetaX   49
N May 4, 2019 by NoDealsHere
Source: Use your common sense! (enough is enough)
Some users don't want to learn, some other simply ignore advises.
But please follow the following guideline:


To make it short: ALWAYS USE YOUR COMMON SENSE IF POSTING!
If you don't have common sense, don't post.


More specifically:

For new threads:


a) Good, meaningful title:
The title has to say what the problem is about in best way possible.
If that title occured already, it's definitely bad. And contest names aren't good either.
That's in fact a requirement for being able to search old problems.

Examples:
Bad titles:
- "Hard"/"Medium"/"Easy" (if you find it so cool how hard/easy it is, tell it in the post and use a title that tells us the problem)
- "Number Theory" (hey guy, guess why this forum's named that way¿ and is it the only such problem on earth¿)
- "Fibonacci" (there are millions of Fibonacci problems out there, all posted and named the same...)
- "Chinese TST 2003" (does this say anything about the problem¿)
Good titles:
- "On divisors of a³+2b³+4c³-6abc"
- "Number of solutions to x²+y²=6z²"
- "Fibonacci numbers are never squares"


b) Use search function:
Before posting a "new" problem spend at least two, better five, minutes to look if this problem was posted before. If it was, don't repost it. If you have anything important to say on topic, post it in one of the older threads.
If the thread is locked cause of this, use search function.

Update (by Amir Hossein). The best way to search for two keywords in AoPS is to input
[code]+"first keyword" +"second keyword"[/code]
so that any post containing both strings "first word" and "second form".


c) Good problem statement:
Some recent really bad post was:
[quote]$lim_{n\to 1}^{+\infty}\frac{1}{n}-lnn$[/quote]
It contains no question and no answer.
If you do this, too, you are on the best way to get your thread deleted. Write everything clearly, define where your variables come from (and define the "natural" numbers if used). Additionally read your post at least twice before submitting. After you sent it, read it again and use the Edit-Button if necessary to correct errors.


For answers to already existing threads:


d) Of any interest and with content:
Don't post things that are more trivial than completely obvious. For example, if the question is to solve $x^{3}+y^{3}=z^{3}$, do not answer with "$x=y=z=0$ is a solution" only. Either you post any kind of proof or at least something unexpected (like "$x=1337, y=481, z=42$ is the smallest solution). Someone that does not see that $x=y=z=0$ is a solution of the above without your post is completely wrong here, this is an IMO-level forum.
Similar, posting "I have solved this problem" but not posting anything else is not welcome; it even looks that you just want to show off what a genius you are.

e) Well written and checked answers:
Like c) for new threads, check your solutions at least twice for mistakes. And after sending, read it again and use the Edit-Button if necessary to correct errors.



To repeat it: ALWAYS USE YOUR COMMON SENSE IF POSTING!


Everything definitely out of range of common sense will be locked or deleted (exept for new users having less than about 42 posts, they are newbies and need/get some time to learn).

The above rules will be applied from next monday (5. march of 2007).
Feel free to discuss on this here.
49 replies
ZetaX
Feb 27, 2007
NoDealsHere
May 4, 2019
Train yourself on folklore NT FE ideas
Assassino9931   3
N 22 minutes ago by MathLuis
Source: Bulgaria Spring Mathematical Competition 2025 9.4
Determine all functions $f: \mathbb{Z}_{>0} \to \mathbb{Z}_{>0}$ such that $f(a) + 2ab + 2f(b)$ divides $f(a)^2 + 4f(b)^2$ for any positive integers $a$ and $b$.
3 replies
Assassino9931
Mar 30, 2025
MathLuis
22 minutes ago
IMO ShortList 1998, number theory problem 2
orl   16
N 23 minutes ago by littlefox_amc
Source: IMO ShortList 1998, number theory problem 2
Determine all pairs $(a,b)$ of real numbers such that $a \lfloor bn \rfloor =b \lfloor an \rfloor $ for all positive integers $n$. (Note that $\lfloor x\rfloor $ denotes the greatest integer less than or equal to $x$.)
16 replies
orl
Oct 22, 2004
littlefox_amc
23 minutes ago
Nice one
Blacklord   9
N 38 minutes ago by Stear14
Source: ....
Find all integers numbers (a,b,c) such that
$a/b + b/c + c/a =3$
9 replies
Blacklord
Jan 26, 2017
Stear14
38 minutes ago
IMO Shortlist 2013, Algebra #2
lyukhson   27
N 41 minutes ago by ezpotd
Source: IMO Shortlist 2013, Algebra #2
Prove that in any set of $2000$ distinct real numbers there exist two pairs $a>b$ and $c>d$ with $a \neq c$ or $b \neq d $, such that \[ \left| \frac{a-b}{c-d} - 1 \right|< \frac{1}{100000}. \]
27 replies
lyukhson
Jul 9, 2014
ezpotd
41 minutes ago
center of (XYZ) lies on a fixed circle
VicKmath7   10
N an hour ago by Blackbeam999
Source: All-Russian 2022 11.3
An acute-angled triangle $ABC$ is fixed on a plane with largest side $BC$. Let $PQ$ be an arbitrary diameter of its circumscribed circle, and the point $P$ lies on the smaller arc $AB$, and the point $Q$ is on the smaller arc $AC$. Points $X, Y, Z$ are feet of perpendiculars dropped from point $P$ to the line $AB$, from point $Q$ to the line $AC$ and from point $A$ to line $PQ$. Prove that the center of the circumscribed circle of triangle $XYZ$ lies on a fixed circle.
10 replies
VicKmath7
Apr 19, 2022
Blackbeam999
an hour ago
a/b+b/c+c/a=3
ilovemath0402   3
N 2 hours ago by Stear14
Find all integer $a,b,c$ such that
$$\dfrac{a}{b}+\dfrac{b}{c}+\dfrac{c}{a}=3$$some confuse
3 replies
ilovemath0402
Jan 1, 2025
Stear14
2 hours ago
Hard Functional Equation in the Complex Numbers
yaybanana   3
N 3 hours ago by Burmf
Source: Own
Find all functions $f:\mathbb {C}\rightarrow \mathbb {C}$, s.t :

$f(xf(y)) + f(x^2+y) = f(x+y)x + f(f(y))$

for all $x,y \in \mathbb{C}$
3 replies
yaybanana
Apr 9, 2025
Burmf
3 hours ago
xf(x + xy) = xf(x) + f(x^2)f(y)
orl   15
N 3 hours ago by MathIQ.
Source: MEMO 2008, Team, Problem 5
Determine all functions $ f: \mathbb{R} \mapsto \mathbb{R}$ such that
\[ x f(x + xy) = x f(x) + f \left( x^2 \right) f(y) \quad  \forall  x,y \in \mathbb{R}.\]
15 replies
orl
Sep 10, 2008
MathIQ.
3 hours ago
points on sides of a triangle, intersections, extensions, ratio of areas wanted
parmenides51   2
N 4 hours ago by MathIQ.
Source: Mexican Mathematical Olympiad 1997 OMM P5
Let $P,Q,R$ be points on the sides $BC,CA,AB$ respectively of a triangle $ABC$. Suppose that $BQ$ and $CR$ meet at $A', AP$ and $CR$ meet at $B'$, and $AP$ and $BQ$ meet at $C'$, such that $AB' = B'C', BC' =C'A'$, and $CA'= A'B'$. Compute the ratio of the area of $\triangle PQR$ to the area of $\triangle ABC$.
2 replies
parmenides51
Jul 28, 2018
MathIQ.
4 hours ago
integer functional equation
ABCDE   156
N 4 hours ago by MathIQ.
Source: 2015 IMO Shortlist A2
Determine all functions $f:\mathbb{Z}\rightarrow\mathbb{Z}$ with the property that \[f(x-f(y))=f(f(x))-f(y)-1\]holds for all $x,y\in\mathbb{Z}$.
156 replies
ABCDE
Jul 7, 2016
MathIQ.
4 hours ago
Three numbers cannot be squares simultaneously
WakeUp   38
N 4 hours ago by SomeonecoolLovesMaths
Source: APMO 2011
Let $a,b,c$ be positive integers. Prove that it is impossible to have all of the three numbers $a^2+b+c,b^2+c+a,c^2+a+b$ to be perfect squares.
38 replies
WakeUp
May 18, 2011
SomeonecoolLovesMaths
4 hours ago
Primes and sets
mathisreaI   40
N 5 hours ago by Tinoba-is-emotional
Source: IMO 2022 Problem 3
Let $k$ be a positive integer and let $S$ be a finite set of odd prime numbers. Prove that there is at most one way (up to rotation and reflection) to place the elements of $S$ around the circle such that the product of any two neighbors is of the form $x^2+x+k$ for some positive integer $x$.
40 replies
mathisreaI
Jul 13, 2022
Tinoba-is-emotional
5 hours ago
Problem G5 - IMO Shortlist 2007
April   30
N 6 hours ago by Double07
Source: ISL 2007, G5, AIMO 2008, TST 3, P2
Let $ ABC$ be a fixed triangle, and let $ A_1$, $ B_1$, $ C_1$ be the midpoints of sides $ BC$, $ CA$, $ AB$, respectively. Let $ P$ be a variable point on the circumcircle. Let lines $ PA_1$, $ PB_1$, $ PC_1$ meet the circumcircle again at $ A'$, $ B'$, $ C'$, respectively. Assume that the points $ A$, $ B$, $ C$, $ A'$, $ B'$, $ C'$ are distinct, and lines $ AA'$, $ BB'$, $ CC'$ form a triangle. Prove that the area of this triangle does not depend on $ P$.

Author: Christopher Bradley, United Kingdom
30 replies
April
Jul 13, 2008
Double07
6 hours ago
Self-evident inequality trick
Lukaluce   16
N 6 hours ago by ErTeeEs06
Source: 2025 Junior Macedonian Mathematical Olympiad P4
Let $x, y$, and $z$ be positive real numbers, such that $x^2 + y^2 + z^2 = 3$. Prove the inequality
\[\frac{x^3}{2 + x} + \frac{y^3}{2 + y} + \frac{z^3}{2 + z} \ge 1.\]When does the equality hold?
16 replies
Lukaluce
May 18, 2025
ErTeeEs06
6 hours ago
Triangle inside triangle which have common thinks
Ege_Saribass   1
N Apr 27, 2025 by Ege_Saribass
Source: Own
An acute triangle $\triangle{ABC}$ is given on the plane. Let the points $D$, $E$ and $F$ be on the sides $BC$, $CA$ and $AB$, respectively. ($D$, $E$ and $F$ are different from the vertices $A$, $B$ and $C$) Also the points $X$, $Y$ and $Z$ are taken such that $DZEXFY$ is an equilateral hexagon which the opposite sides are parallel. Suppose that the circumcenters of $\triangle{ABC}$ and $\triangle XYZ$ are coincident. Then determine the least possible value of:
$$\frac{A(\triangle{XYZ})}{A(\triangle{ABC})}$$Note: $A(\triangle{KLM}) =$ area of $\triangle{KLM}$
1 reply
Ege_Saribass
Apr 26, 2025
Ege_Saribass
Apr 27, 2025
Triangle inside triangle which have common thinks
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Source: Own
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Ege_Saribass
31 posts
#1
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An acute triangle $\triangle{ABC}$ is given on the plane. Let the points $D$, $E$ and $F$ be on the sides $BC$, $CA$ and $AB$, respectively. ($D$, $E$ and $F$ are different from the vertices $A$, $B$ and $C$) Also the points $X$, $Y$ and $Z$ are taken such that $DZEXFY$ is an equilateral hexagon which the opposite sides are parallel. Suppose that the circumcenters of $\triangle{ABC}$ and $\triangle XYZ$ are coincident. Then determine the least possible value of:
$$\frac{A(\triangle{XYZ})}{A(\triangle{ABC})}$$Note: $A(\triangle{KLM}) =$ area of $\triangle{KLM}$
This post has been edited 1 time. Last edited by Ege_Saribass, Apr 27, 2025, 11:10 AM
Reason: missing information
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Ege_Saribass
31 posts
#2
Y by
Answer
Solution
This post has been edited 4 times. Last edited by Ege_Saribass, Apr 30, 2025, 1:00 PM
Reason: e4 e5 Nf3 Nc6
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