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k a April Highlights and 2025 AoPS Online Class Information
jlacosta   0
Apr 2, 2025
Spring is in full swing and summer is right around the corner, what are your plans? At AoPS Online our schedule has new classes starting now through July, so be sure to keep your skills sharp and be prepared for the Fall school year! Check out the schedule of upcoming classes below.

WOOT early bird pricing is in effect, don’t miss out! If you took MathWOOT Level 2 last year, no worries, it is all new problems this year! Our Worldwide Online Olympiad Training program is for high school level competitors. AoPS designed these courses to help our top students get the deep focus they need to succeed in their specific competition goals. Check out the details at this link for all our WOOT programs in math, computer science, chemistry, and physics.

Looking for summer camps in math and language arts? Be sure to check out the video-based summer camps offered at the Virtual Campus that are 2- to 4-weeks in duration. 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 events:
[list][*]April 3rd (Webinar), 4pm PT/7:00pm ET, Learning with AoPS: Perspectives from a Parent, Math Camp Instructor, and University Professor
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April 9th (Webinar), 4:00pm PT/7:00pm ET, Learn about Video-based Summer Camps at the Virtual Campus
[*]April 10th (Math Jam), 4:30pm PT/7:30pm ET, 2025 MathILy and MathILy-Er Math Jam: Multibackwards Numbers
[*]April 22nd (Webinar), 4:00pm PT/7:00pm ET, Competitive Programming at AoPS (USACO).[/list]
Our full course list for upcoming classes is below:
All classes run 7:30pm-8:45pm ET/4:30pm - 5:45pm PT unless otherwise noted.

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0 replies
jlacosta
Apr 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
Website to learn math
hawa   72
N 10 minutes ago by KF329
Hi, I'm kinda curious what website do yall use to learn math, like i dont find any website thats fun to learn math
72 replies
hawa
Apr 9, 2025
KF329
10 minutes ago
Berkeley mini Math Tournament Online is June 7
BerkeleyMathTournament   0
an hour ago
Berkeley mini Math Tournament is a math competition hosted for middle school students once a year. Students compete in multiple rounds: individual round, team round, puzzle round, and relay round.

BmMT 2025 Online will be held on June 7th, and registration is OPEN! Registration is $8 per student. Our website https://berkeley.mt/events/bmmt-2025-online/ has more details about the event, past tests to practice with, and frequently asked questions. We look forward to building community and inspiring students as they explore the world of math!

3 out of 4 of the rounds are completed with a team, so it’s a great opportunity for students to work together. Beyond getting more comfortable with math and becoming better problem solvers, our team is preparing some fun post-competition activities!

Registration is open to students in grades 8 or below. You do not have to be local to the Bay Area or California to register for BmMT Online. Students may register as a team of 1, but it is beneficial to compete on a team of at least 3 due to our scoring guideline and for the experience.

We hope you consider attending, or if you are a parent or teacher, that you encourage your students to think about attending BmMT. Thank you, and once again find more details/register at our website,https://berkeley.mt.
0 replies
BerkeleyMathTournament
an hour ago
0 replies
APMO 2015 P1
aditya21   62
N an hour ago by Tonne
Source: APMO 2015
Let $ABC$ be a triangle, and let $D$ be a point on side $BC$. A line through $D$ intersects side $AB$ at $X$ and ray $AC$ at $Y$ . The circumcircle of triangle $BXD$ intersects the circumcircle $\omega$ of triangle $ABC$ again at point $Z$ distinct from point $B$. The lines $ZD$ and $ZY$ intersect $\omega$ again at $V$ and $W$ respectively.
Prove that $AB = V W$

Proposed by Warut Suksompong, Thailand
62 replies
aditya21
Mar 30, 2015
Tonne
an hour ago
Or statement function
ItzsleepyXD   2
N 2 hours ago by cursed_tangent1434
Source: Own , Mock Thailand Mathematic Olympiad P2
Find all $f: \mathbb{R} \to \mathbb{Z^+}$ such that $$f(x+f(y))=f(x)+f(y)+1\quad\text{ or }\quad f(x)+f(y)-1$$for all real number $x$ and $y$
2 replies
ItzsleepyXD
Yesterday at 9:07 AM
cursed_tangent1434
2 hours ago
Trivial fun Equilateral
ItzsleepyXD   4
N 2 hours ago by cursed_tangent1434
Source: Own , Mock Thailand Mathematic Olympiad P1
Let $ABC$ be a scalene triangle with point $P$ and $Q$ on the plane such that $\triangle BPC , \triangle CQB$ is an equilateral . Let $AB$ intersect $CP$ and $CQ$ at $X$ and $Z$ respectively and $AC$ intersect $BP$ and $BQ$ at $Y$ and $W$ respectively .
Prove that $XY\parallel ZW$
4 replies
ItzsleepyXD
Yesterday at 9:05 AM
cursed_tangent1434
2 hours ago
Geometry Proof
Jackson0423   2
N 3 hours ago by aidan0626
In triangle \( \triangle ABC \), point \( P \) on \( AB \) satisfies \( DB = BC \) and \( \angle DCA = 30^\circ \).
Let \( X \) be the point where the perpendicular from \( B \) to line \( DC \) meets the angle bisector of \( \angle BCA \).
Then, the relation \( AD \cdot DC = BD \cdot AX \) holds.

Prove that \( \triangle ABC \) is an isosceles triangle.
2 replies
Jackson0423
Yesterday at 4:17 PM
aidan0626
3 hours ago
Do not try to case bash lol
ItzsleepyXD   2
N 3 hours ago by cursed_tangent1434
Source: Own , Mock Thailand Mathematic Olympiad P3
Let $n,d\geqslant 6$ be a positive integer such that $d\mid 6^{n!}+1$ .
Prove that $d>2n+6$ .
2 replies
ItzsleepyXD
Yesterday at 9:08 AM
cursed_tangent1434
3 hours ago
N lines cutting each other in the plane
M.J.Espinas   4
N 3 hours ago by Lemmas
Source: Iranian Math Olympiad(Second Round 2016)
Let $l_1,l_2,l_3,...,L_n$ be lines in the plane such that no two of them are parallel and no three of them are concurrent. Let $A$ be the intersection point of lines $l_i,l_j$. We call $A$ an "Interior Point" if there are points $C,D$ on $l_i$ and $E,F$ on $l_j$ such that $A$ is between $C,D$ and $E,F$. Prove that there are at least $\frac{(n-2)(n-3)}{2}$ Interior points.($n>2$)
note: by point here we mean the points which are intersection point of two of $l_1,l_2,...,l_n$.
4 replies
M.J.Espinas
May 5, 2016
Lemmas
3 hours ago
Summer Classes
triggod   0
3 hours ago
Summer STEM Success Series with Fikky Dosunmu!
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Years of Science Bowl and Science Olympiad Experience
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Classes held online via Zoom or Google Meet — flexible scheduling.
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0 replies
triggod
3 hours ago
0 replies
Arbitrary point on BC and its relation with orthocenter
falantrng   25
N 4 hours ago by EeEeRUT
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
25 replies
falantrng
Apr 27, 2025
EeEeRUT
4 hours ago
random achievements
Bummer12345   25
N 4 hours ago by A7456321
What are some random math achievements that you have accomplished but possess no real meaning?

For example, I solved #10 on the 2024 national mathcounts team round, though my team got a 5 Click to reveal hidden text and ended up getting 30-somethingth place
25 replies
Bummer12345
Mar 25, 2025
A7456321
4 hours ago
Hard inequality
JK1603JK   2
N 4 hours ago by arqady
Source: unknown?
Let $a,b,c\in R: abc\neq 0$ and $a+b+c=0$ then prove $$|\frac{a-b}{c}|+|\frac{b-c}{a}|+|\frac{c-a}{b}|\ge 6$$
2 replies
1 viewing
JK1603JK
5 hours ago
arqady
4 hours ago
BMO 2024 SL A5
MuradSafarli   2
N 4 hours ago by ja.


Let \(\mathbb{R}^+ = (0, \infty)\) be the set of positive real numbers.
Find all non-negative real numbers \(c \geq 0\) such that there exists a function \(f : \mathbb{R}^+ \to \mathbb{R}^+\) with the property:
\[
f(y^2f(x) + y + c) = xf(x+y^2)
\]for all \(x, y \in \mathbb{R}^+\).

2 replies
MuradSafarli
Apr 27, 2025
ja.
4 hours ago
Something nice
KhuongTrang   29
N 4 hours ago by arqady
Source: own
Problem. Given $a,b,c$ be non-negative real numbers such that $ab+bc+ca=1.$ Prove that

$$\sqrt{a+1}+\sqrt{b+1}+\sqrt{c+1}\le 1+2\sqrt{a+b+c+abc}.$$
29 replies
KhuongTrang
Nov 1, 2023
arqady
4 hours ago
Hello friends
bibidi_skibidi   9
N Apr 16, 2025 by giratina3
Now unfortunately I don't know the difficulty of the problems posted here but I'll try to replicate:

Bob has 20 apples and 19 oranges. How many ways can he split the fruits between 7 people if each person must have at least 1 apple and 2 oranges?

After looking at the other posters I realized just how bashy this is

Also I can only edit this message for now since new AoPS users can only send 6 messages every day
9 replies
bibidi_skibidi
Apr 15, 2025
giratina3
Apr 16, 2025
Hello friends
G H J
G H BBookmark kLocked kLocked NReply
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bibidi_skibidi
5 posts
#1 • 2 Y
Y by aidan0626, GodGodGodGodGoose
Now unfortunately I don't know the difficulty of the problems posted here but I'll try to replicate:

Bob has 20 apples and 19 oranges. How many ways can he split the fruits between 7 people if each person must have at least 1 apple and 2 oranges?

After looking at the other posters I realized just how bashy this is

Also I can only edit this message for now since new AoPS users can only send 6 messages every day
This post has been edited 1 time. Last edited by bibidi_skibidi, Apr 15, 2025, 4:19 AM
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aidan0626
1882 posts
#2
Y by
Hi :)
This is standard stars and bars, there are $\binom{19}{6}$ ways to split the apples and $\binom{11}{6}$ ways to split the oranges, and you just multiply those two together to get the final answer.
Z K Y
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Soupboy0
349 posts
#3
Y by
bro i got sniped :rotfl:
Z K Y
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maxamc
568 posts
#4
Y by
aidan0626 wrote:
Hi :)
This is standard stars and bars, there are $\binom{19}{6}$ ways to split the apples and $\binom{11}{6}$ ways to split the oranges, and you just multiply those two together to get the final answer.

Wolfram Alpha gives 12534984 as our final answer (impossible to compute)
Z K Y
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fluffyyyyyyy
1 post
#5
Y by
hello sabko
Z K Y
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Leeoz
178 posts
#6
Y by
maxamc wrote:
aidan0626 wrote:
Hi :)
This is standard stars and bars, there are $\binom{19}{6}$ ways to split the apples and $\binom{11}{6}$ ways to split the oranges, and you just multiply those two together to get the final answer.

Wolfram Alpha gives 12534984 as our final answer (impossible to compute)

its not "impossible" :P
Z K Y
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Thayaden
1361 posts
#7
Y by
bibidi_skibidi wrote:
Now unfortunately I don't know the difficulty of the problems posted here but I'll try to replicate:

Bob has 20 apples and 19 oranges. How many ways can he split the fruits between 7 people if each person must have at least 1 apple and 2 oranges?

After looking at the other posters I realized just how bashy this is

Also I can only edit this message for now since new AoPS users can only send 6 messages every day

Start by giving away the required fruit this leaves 18 fruit for grabs namely 13 ap0pels and 5 oranges we set up stars and bars for extras and get (13+6)! but yet no oranges is diffrent from another orange and there are 5! ways to arage oranges and 13! ways to arange appels and 6! ways to arange bars so I think our answer is $\boxed{\frac{(18+6)!}{5!13!6!}}$ is what I got
Z K Y
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maxamc
568 posts
#8
Y by
Thayaden wrote:
bibidi_skibidi wrote:
Now unfortunately I don't know the difficulty of the problems posted here but I'll try to replicate:

Bob has 20 apples and 19 oranges. How many ways can he split the fruits between 7 people if each person must have at least 1 apple and 2 oranges?

After looking at the other posters I realized just how bashy this is

Also I can only edit this message for now since new AoPS users can only send 6 messages every day

Start by giving away the required fruit this leaves 18 fruit for grabs namely 13 ap0pels and 5 oranges we set up stars and bars for extras and get (13+6)! but yet no oranges is diffrent from another orange and there are 5! ways to arage oranges and 13! ways to arange appels and 6! ways to arange bars so I think our answer is $\boxed{\frac{(18+6)!}{5!13!6!}}$ is what I got

Your answer is 1153218528, not equal to my Wolfram Alpha answer described above, unfortunately wrong I think.
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BS2012
1027 posts
#9
Y by
its just Solution sketch which is the same as the 2nd post
This post has been edited 3 times. Last edited by BS2012, Apr 16, 2025, 12:52 AM
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giratina3
500 posts
#10
Y by
This is not bashy at all if you know Stars and Bars. I would recommend reading the later sections of Intro to Counting and Probability for more information.
This post has been edited 1 time. Last edited by giratina3, Apr 16, 2025, 2:57 AM
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