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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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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
Jbmo 2011 Problem 4
Eukleidis   13
N 2 hours ago by Adventure1000
Source: Jbmo 2011
Let $ABCD$ be a convex quadrilateral and points $E$ and $F$ on sides $AB,CD$ such that
\[\tfrac{AB}{AE}=\tfrac{CD}{DF}=n\]

If $S$ is the area of $AEFD$ show that ${S\leq\frac{AB\cdot CD+n(n-1)AD^2+n^2DA\cdot BC}{2n^2}}$
13 replies
Eukleidis
Jun 21, 2011
Adventure1000
2 hours ago
an algebra question
kjhgyuio   1
N 2 hours ago by aidan0626
.........
1 reply
kjhgyuio
2 hours ago
aidan0626
2 hours ago
1500th Post!
PikaPika999   120
N 2 hours ago by Craftybutterfly
I hit my 1500th post!!
This is just gonna be a 24 game thread then ig :)
You can't use concatenation
To start off, ig make 24 using the following numbers:

3,3,8,8

EDIT: NOTE THAT I DIDN'T MEAN TO GET THIS FROM THE TEAM CONTEST THING! I GOT THIS FROM MY FRIENDS, SO PLEASE STOP BUGGING ME ABOUT THIS
120 replies
PikaPika999
May 1, 2025
Craftybutterfly
2 hours ago
we can find one pair of a boy and a girl
orl   16
N 2 hours ago by ezpotd
Source: Vietnam TST 2001 for the 42th IMO, problem 3
Some club has 42 members. It’s known that among 31 arbitrary club members, we can find one pair of a boy and a girl that they know each other. Show that from club members we can choose 12 pairs of knowing each other boys and girls.
16 replies
orl
Jun 26, 2005
ezpotd
2 hours ago
teleporting wizard starts on point (2017, 101), 4 moves
parmenides51   1
N 2 hours ago by jasperE3
Source: 2018 USAIMEO #2 p5 (Mock AIME -USAJMO) https://artofproblemsolving.com/community/c594864h1572209p9658908
A teleporting wizard starts on the point $(2017, 101)$ and can teleport to other Cartesian coordinates with only $1$ of $4$ moves: $(x, y) \to (x + y, y)$, $(x, y) \to (x - y, y)$ when $x > y$, $(x, y) \to (x, x + y)$, and $(x, y) \to (x, y - x)$ when $y > x$.

(a) Let $P(x)$ be any polynomial with positive integer coefficients that passes through $(0, 0)$. Show that for all such $P(x)$, there exists a unique point on the curve where the wizard can land on.

(b) For each $P(x)$, let $S$ be this unique point. Find the equation of the graph that contains all potential $S$.
1 reply
parmenides51
Nov 17, 2023
jasperE3
2 hours ago
IMO ShortList 2001, combinatorics problem 1
orl   33
N 2 hours ago by ihategeo_1969
Source: IMO ShortList 2001, combinatorics problem 1
Let $A = (a_1, a_2, \ldots, a_{2001})$ be a sequence of positive integers. Let $m$ be the number of 3-element subsequences $(a_i,a_j,a_k)$ with $1 \leq i < j < k \leq 2001$, such that $a_j = a_i + 1$ and $a_k = a_j + 1$. Considering all such sequences $A$, find the greatest value of $m$.
33 replies
orl
Sep 30, 2004
ihategeo_1969
2 hours ago
CooL geo
Pomegranat   0
3 hours ago
Source: Idk

In triangle \( ABC \), \( D \) is the midpoint of \( BC \). \( E \) is an arbitrary point on \( AC \). Let \( S \) be the intersection of \( AD \) and \( BE \). The line \( CS \) intersects with the circumcircle of \( ACD \), for the second time at \( K \). \( P \) is the circumcenter of triangle \( ABE \). Prove that \( PK \perp CK \).
0 replies
1 viewing
Pomegranat
3 hours ago
0 replies
Coefficient Problem
P162008   2
N 3 hours ago by cazanova19921
Consider the polynomial $g(x) = \prod_{i=1}^{7} \left(1 + x^{i!} + x^{2i!} + x^{3i!} + \cdots + x^{(i-1)i!} + x^{ii!}\right)$
Find the coefficient of $x^{2025}$ in the expansion of $g(x).$
2 replies
P162008
Yesterday at 12:16 PM
cazanova19921
3 hours ago
Shooting An Invisible Tank
Aryan27   0
3 hours ago
Source: 239 MO
An invisible tank is on a $100 \times 100 $ table. A cannon can fire at any $k$ cells of the board after that the tank will move to one of the adjacent cells (by side). Then the process is repeated. Find the smallest value of $k$ such that the cannon can definitely shoot the tank after some time.
0 replies
Aryan27
3 hours ago
0 replies
Showing Tangency
Itoz   1
N 3 hours ago by ja.
Source: Own
The circumcenter of $\triangle ABC$ is $O$. Line $AO$ meets line $BC$ at point $D$, and there is a point $E$ on $\odot(ABC)$ such that $AE \perp BC$. Line $DE$ intersects $\odot(ABC)$ at point $F$. The perpendicular bisector of line segment $BC$ intersects line $AB$ at point $K$, and line $AB$ intersects $\odot(CFK)$ at point $L$.

Prove that $\odot(AFL)$ is tangent to $\odot (OBC)$.
1 reply
Itoz
Yesterday at 1:57 PM
ja.
3 hours ago
2-var inequality
sqing   7
N 3 hours ago by mathuz
Source: Own
Let $ a,b\geq 0    $. Prove that
$$ \frac{a }{a^2+2b^2+1}+ \frac{b }{b^2+2a^2+1}\leq \frac{1}{\sqrt{3}} $$$$   \frac{a }{2a^2+ b^2+2ab+1}+ \frac{b }{2b^2+ a^2+2ab+1}  \leq \frac{1}{\sqrt{5}} $$$$ \frac{a }{2a^2+ b^2+ ab+1}+ \frac{b }{2b^2+ a^2+ ab+1} \leq \frac{1}{2} $$$$\frac{a }{a^2+2b^2+2ab+1}+ \frac{b }{b^2+2a^2+2ab+1}\leq \frac{1}{2} $$
7 replies
sqing
Today at 1:39 AM
mathuz
3 hours ago
9 zeroes!.
ericheathclifffry   4
N 4 hours ago by valisaxieamc
i personally have no idea
4 replies
ericheathclifffry
Today at 1:07 AM
valisaxieamc
4 hours ago
How many ways to spell the word COUNT
yinglinwu   3
N 4 hours ago by yinglinwu
This is the problem 2.771 from the book Competition Math For Middle School. The printed answer is 16, which is obtained by going through the triangle. I have no idea about what's going on there. Can anyone help explain please?

BTW, my understanding about a way to spell COUNT is simply to choose an order of those letters and write down them one by one at their designated locations, like writing down U first at the 3rd location, then O at the 2nd position, N at 4th, T at 5th, and C at 1st. Therefore, in total we should have 5! ways to spell the word.
3 replies
yinglinwu
Yesterday at 7:17 PM
yinglinwu
4 hours ago
(Restored) FTW and AMC Prep Forum
stjwyl   50
N 5 hours ago by fossasor
PatTheKing806 and Sadas123 created a private forum for people to do math with friends. Doing math in a forum can make it more fun and help motivate people to achieve their goals. We have currencies and games, just like a normal forum.

This is similar to the 'AMC 8 Prep Buddies' Forum (also created by pattheking and sadas), but if anybody wants to join, just type, /join and one of us will add you. This is also a FTW Forum if you are curious too!

The link for this forum is here

Due to a recent event where someone trolled the original forum, all admins were removed from the forum. At that time, no one could restore the original without going through a lot of trouble and using a lot of time. We made a backup forum that was trolled again (presumable by the same admin), so now we are back with a forum with only the most trusted admins.

Please /signup here, not in the now outdated thread.
Thanks!

~stjwyl
50 replies
stjwyl
Jan 4, 2025
fossasor
5 hours ago
Geometry Transformation Problems
ReticulatedPython   7
N Apr 22, 2025 by ReticulatedPython
Problem 1:
A regular hexagon of side length $1$ is rotated $360$ degrees about one side. The space through which the hexagon travels during the rotation forms a solid. Find the volume of this solid.

Problem 2:

A regular octagon of side length $1$ is rotated $360$ degrees about one side. The space through which the octagon travels through during the rotation forms a solid. Find the volume of this solid.

Source:Own

Hint

Useful Formulas
7 replies
ReticulatedPython
Apr 17, 2025
ReticulatedPython
Apr 22, 2025
Geometry Transformation Problems
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ReticulatedPython
617 posts
#1
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Problem 1:
A regular hexagon of side length $1$ is rotated $360$ degrees about one side. The space through which the hexagon travels during the rotation forms a solid. Find the volume of this solid.

Problem 2:

A regular octagon of side length $1$ is rotated $360$ degrees about one side. The space through which the octagon travels through during the rotation forms a solid. Find the volume of this solid.

Source:Own

Hint

Useful Formulas
This post has been edited 11 times. Last edited by ReticulatedPython, Apr 21, 2025, 3:33 PM
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jb2015007
1931 posts
#2
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ack i hate transformation problems and i suck at them so ill do this lol ill do it when i get home from school
@reticulated python check out the problem i posted in the intro to geo message board its real interesting
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ReticulatedPython
617 posts
#3
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Ok I will.
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ReticulatedPython
617 posts
#4
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Anyone want to give it a try?
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cheltstudent
621 posts
#5
Y by
wait which intro to geo class is this
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ReticulatedPython
617 posts
#6
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\bump :)
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ReticulatedPython
617 posts
#7
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I will present the solution to problem 1 and see if anyone can use that to solve problem 2. Solution
This post has been edited 2 times. Last edited by ReticulatedPython, Apr 21, 2025, 7:26 PM
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ReticulatedPython
617 posts
#8
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Alright I will give the answer to problem 2; the method is similar to that of problem 1. Answer
This post has been edited 1 time. Last edited by ReticulatedPython, Apr 22, 2025, 3:31 PM
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