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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:
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[*]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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0 replies
jlacosta
May 1, 2025
0 replies
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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
J
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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
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When to look at solutions - pre calc
omerrob13   1
N 39 minutes ago by abartoha
Hey all.
I am doing the precalc book, and unfortunately, im getting into the habit of looking in the solutions quite fast on a problem I did not able to make any progress on.
My goal is mainly to develop problem solving and reasonning skills.

I divide the problems in AOPS to 2:

- Challenge problems at the end of the of each chapter.
- The problems that teach you the material itself, and the problems at the end of each section (1.1,1.2, etc...)

For non challenging problems, It takes around 20 mins of me not be able to solve a problem, and look at the solutions for it

Is it too little?
My goal is mainly to develop problem solving and reasoning skills.
I'm not sure if it's too little time to bring to a regular problem, or its ok to give 20 mins to a problem and continue if making no progress.
1 reply
omerrob13
2 hours ago
abartoha
39 minutes ago
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an algebra problem
Asyrafr09   1
N an hour ago by abartoha
Determine all real number($x,y,z$) that satisfy
$$x=1+\sqrt{y-z^2}$$$$y=1+\sqrt{z-x^2}$$$$z=1+\sqrt{x-y^2}$$
1 reply
Asyrafr09
an hour ago
abartoha
an hour ago
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Arbitrary point on BC and its relation with orthocenter
falantrng   31
N an hour ago by NZP_IMOCOMP4
Source: Balkan MO 2025 P2
In an acute-angled triangle \(ABC\), \(H\) be the orthocenter of it and \(D\) be any point on the side \(BC\). The points \(E, F\) are on the segments \(AB, AC\), respectively, such that the points \(A, B, D, F\) and \(A, C, D, E\) are cyclic. The segments \(BF\) and \(CE\) intersect at \(P.\) \(L\) is a point on \(HA\) such that \(LC\) is tangent to the circumcircle of triangle \(PBC\) at \(C.\) \(BH\) and \(CP\) intersect at \(X\). Prove that the points \(D, X, \) and \(L\) lie on the same line.

Proposed by Theoklitos Parayiou, Cyprus
31 replies
falantrng
Apr 27, 2025
NZP_IMOCOMP4
an hour ago
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IMO Genre Predictions
ohiorizzler1434   23
N an hour ago by ohiorizzler1434
Everybody, with IMO upcoming, what are you predictions for the problem genres?


Personally I predict: predict
23 replies
ohiorizzler1434
Yesterday at 6:51 AM
ohiorizzler1434
an hour ago
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Number theory
gggzul   0
an hour ago
Is the number
$$10^{32}+10^{28}+...+10^4+1$$a perfect square?
0 replies
gggzul
an hour ago
0 replies
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3 var inequality
sqing   1
N 2 hours ago by sqing
Source: Own
Let $ a,b,c>0 . $ Prove that
$$ \left(1 +\frac{a}{b}\right)\left(1+\frac{b}{c}\right)\left(1+\frac{c}{a}\right )\geq \frac{8}{3}\left(1+\frac{a+b}{b+c}+ \frac{b+c}{a+b}\right)$$$$ \left(1 +\frac{a^2}{b^2}\right)\left(1+\frac{b^2}{c^2}\right)\left(1+\frac{c^2}{a^2}\right )\geq \frac{8}{3}\left( 1+\frac{a^2+bc}{b^2+ca}+\frac{b^2+ca }{a^2+bc}\right)$$
1 reply
sqing
May 1, 2025
sqing
2 hours ago
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Classic FE
BR1F1SZ   4
N 2 hours ago by User141208
Source: Argentina IberoAmerican TST 2024 P5
Let \( \mathbb R \) be the set of real numbers. Find all functions \( f: \mathbb{R} \to \mathbb{R} \) such that, for all real numbers \( x \) and \( y \), the following equation holds:$$\big (x^2-y^2\big )f\big (xy\big )=xf\big (x^2y\big )-yf\big (xy^2\big ).$$
4 replies
BR1F1SZ
Aug 9, 2024
User141208
2 hours ago
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Maybe LTE
navredras   2
N 2 hours ago by Blackbeam999
Source: Bulgaria 1997
Let $ n $ be a positive integer. If $ 3^n-2^n $ is a power of a prime number, prove that $ n $ is also prime.
2 replies
navredras
Jan 4, 2015
Blackbeam999
2 hours ago
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Sequence Gets Ratio’d
v4913   21
N 2 hours ago by cursed_tangent1434
Source: EGMO 2023/1
There are $n \ge 3$ positive real numbers $a_1, a_2, \dots, a_n$. For each $1 \le i \le n$ we let $b_i = \frac{a_{i-1} + a_{i+1}}{a_i}$ (here we define $a_0$ to be $a_n$ and $a_{n+1}$ to be $a_1$). Assume that for all $i$ and $j$ in the range $1$ to $n$, we have $a_i \le a_j$ if and only if $b_i \le b_j$.
Prove that $a_1 = a_2 = \dots = a_n$.
21 replies
v4913
Apr 16, 2023
cursed_tangent1434
2 hours ago
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Functional equation on (0,infinity)
mathwizard888   56
N 2 hours ago by Adywastaken
Source: 2016 IMO Shortlist A4
Find all functions $f:(0,\infty)\rightarrow (0,\infty)$ such that for any $x,y\in (0,\infty)$, $$xf(x^2)f(f(y)) + f(yf(x)) = f(xy) \left(f(f(x^2)) + f(f(y^2))\right).$$
56 replies
mathwizard888
Jul 19, 2017
Adywastaken
2 hours ago
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Orthocenter
jayme   6
N 2 hours ago by Sadigly
Dear Mathlinkers,

1. ABC an acuatangle triangle
2. H the orthcenter of ABC
3. DEF the orthic triangle of ABC
4. A* the midpoint of AH
5. X the point of intersection of AH and EF.

Prove : X is the orthocenter of A*BC.

Sincerely
Jean-Louis
6 replies
jayme
Mar 25, 2015
Sadigly
2 hours ago
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f_n(x)=\sum sin(nx)/n
Urumqi   4
N 2 hours ago by Urumqi
$F_n(x)=\sum_{k=1}^{n}\frac{\sin (kx)}{k}$, prove that for all $x \in (0,\pi), F_n(x)>0$.

Thanks.
4 replies
Urumqi
Today at 2:13 AM
Urumqi
2 hours ago
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positive integers forming a perfect square
cielblue   2
N 3 hours ago by Pal702004
Find all positive integers $n$ such that $2^n-n^2+1$ is a perfect square.
2 replies
cielblue
Friday at 8:25 PM
Pal702004
3 hours ago
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A Collection of Good Problems from my end
SomeonecoolLovesMaths   2
N 3 hours ago by SomeonecoolLovesMaths
This is a collection of good problems and my respective attempts to solve them. I would like to encourage everyone to post their solutions to these problems, if any. This will not only help others verify theirs but also perhaps bring forward a different approach to the problem. I will constantly try to update the pool of questions.

The difficulty level of these questions vary from AMC 10 to AIME. (Although the main pool of questions were prepared as a mock test for IOQM over the years)

Problem 1

Problem 2

Problem 3
2 replies
SomeonecoolLovesMaths
3 hours ago
SomeonecoolLovesMaths
3 hours ago
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Two problems
Vulch   1
N Apr 10, 2025 by Lankou
Solve the following problems:
1 reply
Vulch
Apr 10, 2025
Lankou
Apr 10, 2025
J
Two problems
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Reveal topic tags
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Vulch
2690 posts
Vulch
#1 h  Apr 10, 2025, 10:58 AM
Y by
Solve the following problems:
Attachments:
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This post has been deleted. Click here to see post.
Lankou
1396 posts
Lankou
#2 h  Apr 10, 2025, 11:47 AM
Y by
27.
Using Vieta you get $c=7\cdot8=56$ and $-b=8-3=5$, $b=-5$

28.
If $\Delta<0$ then $f(x)\neq0$
if $\Delta>0$ then $f(x)=0$ has two real roots, one of them may be $0$
This post has been edited 1 time. Last edited by Lankou, Apr 10, 2025, 11:51 AM
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