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k a March Highlights and 2025 AoPS Online Class Information
jlacosta   0
Mar 2, 2025
March is the month for State MATHCOUNTS competitions! Kudos to everyone who participated in their local chapter competitions and best of luck to all going to State! Join us on March 11th for a Math Jam devoted to our favorite Chapter competition problems! Are you interested in training for MATHCOUNTS? Be sure to check out our AMC 8/MATHCOUNTS Basics and Advanced courses.

Are you ready to level up with Olympiad training? Registration is open with early bird pricing available for our WOOT programs: MathWOOT (Levels 1 and 2), CodeWOOT, PhysicsWOOT, and ChemWOOT. What is WOOT? WOOT stands for Worldwide Online Olympiad Training and is a 7-month high school math Olympiad preparation and testing program that brings together many of the best students from around the world to learn Olympiad problem solving skills. Classes begin in September!

Do you have plans this summer? There are so many options to fit your schedule and goals whether attending a summer camp or taking online classes, it can be a great break from the routine of the school year. Check out our summer courses at AoPS Online, or if you want a math or language arts class that doesn’t have homework, but is an enriching summer experience, our AoPS Virtual Campus summer camps may be just the ticket! We are expanding our locations for our AoPS Academies across the country with 15 locations so far and new campuses opening in Saratoga CA, Johns Creek GA, and the Upper West Side NY. Check out this page for summer camp information.

Be sure to mark your calendars for the following events:
[list][*]March 5th (Wednesday), 4:30pm PT/7:30pm ET, HCSSiM Math Jam 2025. Amber Verser, Assistant Director of the Hampshire College Summer Studies in Mathematics, will host an information session about HCSSiM, a summer program for high school students.
[*]March 6th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar on Math Competitions from elementary through high school. Join us for an enlightening session that demystifies the world of math competitions and helps you make informed decisions about your contest journey.
[*]March 11th (Tuesday), 4:30pm PT/7:30pm ET, 2025 MATHCOUNTS Chapter Discussion MATH JAM. AoPS instructors will discuss some of their favorite problems from the MATHCOUNTS Chapter Competition. All are welcome!
[*]March 13th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar about Summer Camps at the Virtual Campus. Transform your summer into an unforgettable learning adventure! From elementary through high school, we offer dynamic summer camps featuring topics in mathematics, language arts, and competition preparation - all designed to fit your schedule and ignite your passion for learning.[/list]
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0 replies
jlacosta
Mar 2, 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
quadratics
luciazhu1105   21
N 41 minutes ago by cheltstudent
I really need help on quadratics and I don't know why I also kinda need a bit of help on graphing functions and finding the domain and range of them.
21 replies
luciazhu1105
Feb 14, 2025
cheltstudent
41 minutes ago
super duper ez radax problem
iStud   3
N 43 minutes ago by phi22_7
Source: Monthly Contest KTOM March 2025 P1 Essay
Given an acute triangle $ABC$ with $BC<AB<AC$. Points $D$ and $E$ are on $AB$ and $AC$ respectively such that $DB=BC=CE$. Lines $CD$ and $BE$ meet at $F$. $I$ is the incenter of $\triangle{ABC}$ and $H$ is the orthocenter of $\triangle{DEF}$. $\omega_b$ and $\omega_c$ are circles with diameter $BD$ and $CE$, respectively, intersecting each other at points $X$ and $Y$. Prove that $I$ and $H$ lie on $XY$.

Hint
3 replies
iStud
Mar 18, 2025
phi22_7
43 minutes ago
Elegant inequality
SunnyEvan   0
an hour ago
Source: proposed by Zhenping An
Let $a$, $b$, $c$, $d$ be non-negative real numbers such that
\[2a+2b+2c+2d+ab+bc+cd+da+3=abcd.\]prove that : \[\sqrt[4]{abc}+\sqrt[4]{bcd}+\sqrt[4]{cda}+\sqrt[4]{dab}\le\sqrt[4]{27(1+a)(1+b)(1+c)(1+d)}.\]
0 replies
SunnyEvan
an hour ago
0 replies
Prime and square
m4thbl3nd3r   0
an hour ago
Find all triplets of prime number $(p,q,r)$ such that $$(p^2+3p)(q^2+3q)(r^2+3r)$$is a perfect square.
0 replies
m4thbl3nd3r
an hour ago
0 replies
Hard number theory problem
Omid Hatami   16
N an hour ago by quantam13
Source: Iran 2002
$\pi(n)$ is the number of primes that are not bigger than $n$. For $n=2,3,4,6,8,33,\dots$ we have $\pi(n)|n$. Does exist infinitely many integers $n$ that $\pi(n)|n$?
16 replies
Omid Hatami
Apr 9, 2004
quantam13
an hour ago
Maximize non-intersecting/perpendicular diagonals!
cjquines0   36
N 2 hours ago by endless_abyss
Source: 2016 IMO Shortlist C5
Let $n \geq 3$ be a positive integer. Find the maximum number of diagonals in a regular $n$-gon one can select, so that any two of them do not intersect in the interior or they are perpendicular to each other.
36 replies
cjquines0
Jul 19, 2017
endless_abyss
2 hours ago
Nice function question
srnjbr   2
N 2 hours ago by pco
Find all functions f:R+--R+ such that for all a,b>0, f(af(b)+a)(f(bf(a))+a)=1
2 replies
srnjbr
Today at 4:28 AM
pco
2 hours ago
Inequality with real numbers
JK1603JK   2
N 2 hours ago by SunnyEvan
Source: unknown
Let a,b,c are real numbers. Prove that (a^3+b^3+c^3+3abc)^4+(a+b+c)^3(a+b-c)^3(-a+b+c)^3(a-b+c)^3>=0
2 replies
JK1603JK
6 hours ago
SunnyEvan
2 hours ago
Mathhhhh
mathbetter   10
N 2 hours ago by togrulhamidli2011
Three turtles are crawling along a straight road heading in the same
direction. "Two other turtles are behind me," says the first turtle. "One turtle is
behind me and one other is ahead," says the second. "Two turtles are ahead of me
and one other is behind," says the third turtle. How can this be possible?
10 replies
mathbetter
Mar 20, 2025
togrulhamidli2011
2 hours ago
SONG circle?
YaoAOPS   1
N 3 hours ago by bin_sherlo
Source: own?
Let triangle $ABC$ have incenter $I$ and intouch triangle $DEF$. Let the circumcircle of $ABC$ intersect $(AEF)$ at $S$ and have center $O$. Let $N$ be the midpoint of arc $BAC$ on the circumcircle. Suppose quadrilateral $SONG$ is cyclic such that $X = SN \cap OG$ lies on $BC$. Show that $\angle XGD = 90^\circ$.
1 reply
YaoAOPS
5 hours ago
bin_sherlo
3 hours ago
A touching question on perpendicular lines
Tintarn   1
N 3 hours ago by Mathzeus1024
Source: Bundeswettbewerb Mathematik 2025, Round 1 - Problem 3
Let $k$ be a semicircle with diameter $AB$ and midpoint $M$. Let $P$ be a point on $k$ different from $A$ and $B$.

The circle $k_A$ touches $k$ in a point $C$, the segment $MA$ in a point $D$, and additionally the segment $MP$. The circle $k_B$ touches $k$ in a point $E$ and additionally the segments $MB$ and $MP$.

Show that the lines $AE$ and $CD$ are perpendicular.
1 reply
Tintarn
Mar 17, 2025
Mathzeus1024
3 hours ago
Factoring Marathon
pican   1437
N Today at 5:59 AM by aidan0626
Hello guys,
I think we should start a factoring marathon. Post your solutions like this SWhatever, and your problems like this PWhatever. Please make your own problems, and I'll start off simple: P1
1437 replies
pican
Aug 4, 2015
aidan0626
Today at 5:59 AM
Confirming a number theoretical result
OlympusHero   1
N Today at 5:14 AM by aidan0626
Prove that $a \cdot c^{-1}+b \cdot d^{-1} = (ad+bc) \cdot (cd)^{-1} \pmod n$ where $\gcd(c,n) = \gcd(d,n) = 1$.
1 reply
OlympusHero
Today at 5:10 AM
aidan0626
Today at 5:14 AM
How to convert base numbers directly without using base 10
DSL13   13
N Today at 5:08 AM by giratina3
I don't understand the topic of how you convert bases directly without going from base 10 to the base that I desire. How do I get from one base to another without the use of base 10?

I watched videos on it but I don't really get the idea.
13 replies
DSL13
Mar 11, 2021
giratina3
Today at 5:08 AM
Boxes & Balls
tpulak   0
Dec 1, 2007
Heres the problem :

"The dimensions of 2 boxes are A by B by C, and D by E by F, respectively. If A<C, D<B, E<A, B<E, and A<F, what is the diameter of the largest largest ball that can fit into both boxes? Express your answer in terms of A,B,C,D,E,F, and/or F"
0 replies
tpulak
Dec 1, 2007
0 replies
Boxes & Balls
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G H BBookmark kLocked kLocked NReply
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tpulak
50 posts
#1 • 1 Y
Y by Adventure10
Heres the problem :

"The dimensions of 2 boxes are A by B by C, and D by E by F, respectively. If A<C, D<B, E<A, B<E, and A<F, what is the diameter of the largest largest ball that can fit into both boxes? Express your answer in terms of A,B,C,D,E,F, and/or F"
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