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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
9 Prodigy AoPS or Khanacadamy
ZMB038   3
N 9 minutes ago by OGMATH
Hey everyone just was wondering what everybody prefers? Try not to fight so this doesn't get locked!
3 replies
ZMB038
2 hours ago
OGMATH
9 minutes ago
functional equation with exponentials
produit   4
N 9 minutes ago by jasperE3
Find all solutions of the real valued functional equation:
f(\sqrt{x^2+y^2})=f(x)f(y).
Here we do not assume f is continuous
4 replies
produit
2 hours ago
jasperE3
9 minutes ago
functional inequality with equality
miiirz30   1
N 11 minutes ago by MR.1
Source: 2025 Euler Olympiad, Round 2
Find all functions \( f : \mathbb{R} \to \mathbb{R} \) such that the following two conditions hold:

1. For all real numbers $a$ and $b$ satisfying $a^2 + b^2 = 1$, We have $f(x) + f(y) \geq f(ax + by)$ for all real numbers $x, y$.

2. For all real numbers $x$ and $y$, there exist real numbers $a$ and $b$, such that $a^2 + b^2 = 1$ and $f(x) + f(y) = f(ax + by)$.

Proposed by Zaza Melikidze, Georgia
1 reply
miiirz30
5 hours ago
MR.1
11 minutes ago
Moving stones on an infinite row
miiirz30   1
N 14 minutes ago by genius_007
Source: 2025 Euler Olympiad, Round 2
We are given an infinite row of cells extending infinitely in both directions. Some cells contain one or more stones. The total number of stones is finite. At each move, the player performs one of the following three operations:

1. Take three stones from some cell, and add one stone to the cells located one cell to the left and one cell to the right, each skipping one cell in between.

2. Take two stones from some cell, and add one stone to the cell one cell to the left, skipping one cell and one stone to the adjacent cell to the right.

3. Take one stone from each of two adjacent cells, and add one stone to the cell to the right of these two cells.

The process ends when no moves are possible. Prove that the process always terminates and the final distribution of stones does not depend on the choices of moves made by the player.

IMAGE

Proposed by Luka Tsulaia, Georgia
1 reply
miiirz30
4 hours ago
genius_007
14 minutes ago
max number of candies
orangefronted   27
N 16 minutes ago by ZMB038
A store sells a strawberry flavoured candy for 1 dollar each. The store offers a promo where every 4 candy wrappers can be exchanged for one candy. If there is no limit to how many times you can exchange candy wrappers for candies, what is the maximum number of candies I can obtain with 100 dollars?
27 replies
orangefronted
Apr 3, 2025
ZMB038
16 minutes ago
Worst math problems
LXC007   4
N 18 minutes ago by notsixtyfour
What is the most egregiously bad problem or solution you have encountered in school?
4 replies
LXC007
Yesterday at 11:42 PM
notsixtyfour
18 minutes ago
Interesting inequalities
sqing   8
N 24 minutes ago by sqing
Source: Own
Let $ a,b,c,d\geq  0 , a+b+c+d \leq 4.$ Prove that
$$a(bc+bd+cd)  \leq \frac{256}{81}$$$$ ab(a+2c+2d ) \leq \frac{256}{27}$$$$  ab(a+3c+3d )  \leq \frac{32}{3}$$$$ ab(c+d ) \leq \frac{64}{27}$$
8 replies
sqing
Yesterday at 1:25 PM
sqing
24 minutes ago
2000 KJMO P1 easy euclidean lemma
RL_parkgong_0106   4
N 29 minutes ago by JH_K2IMO
Source: KJMO 2000
For arbitrary natural number $a$, show that $\gcd(a^3+1, a^7+1)=a+1$.
4 replies
RL_parkgong_0106
Jun 29, 2024
JH_K2IMO
29 minutes ago
Sum floor 2^k/3 from k=0 to 100
v_Enhance   8
N 29 minutes ago by MathIQ.
Source: All-Russian MO 2000
Evaluate the sum \[ \left\lfloor \frac{2^0}{3} \right\rfloor  + \left\lfloor \frac{2^1}{3} \right\rfloor + \left\lfloor \frac{2^2}{3} \right\rfloor  + \cdots + \left\lfloor \frac{2^{1000}}{3} \right\rfloor. \]
8 replies
v_Enhance
Dec 30, 2012
MathIQ.
29 minutes ago
Points on a lattice path lies on a line
navi_09220114   3
N 30 minutes ago by Ianis
Source: TASIMO 2025 Day 1 Problem 3
Let $S$ be a nonempty subset of the points in the Cartesian plane such that for each $x\in S$ exactly one of $x+(0,1)$ or $x+(1,0)$ also belongs to $S$. Prove that for each positive integer $k$ there is a line in the plane (possibly different lines for different $k$) which contains at least $k$ points of $S$.
3 replies
navi_09220114
May 19, 2025
Ianis
30 minutes ago
Graph Theory
ABCD1728   1
N 36 minutes ago by ABCD1728
Can anyone provide the PDF version of "Graphs: an introduction" by Radio Bumbacea (XYZ press), thanks!
1 reply
ABCD1728
Today at 5:32 AM
ABCD1728
36 minutes ago
Inspired by Crux 4975
sqing   4
N an hour ago by sqing
Source: Own
Let $ a,b,c\geq 0 $ and $ a(b +c +bc)=1.$ Prove that
$$a^2+b^2+c^2+ 3abc(a+b+c)\geq 2 $$
4 replies
sqing
Oct 18, 2024
sqing
an hour ago
CMI Entrance 19#6
bubu_2001   7
N an hour ago by Apple_maths60
$(a)$ Compute -
\begin{align*}
\frac{\mathrm{d}}{\mathrm{d}x} \bigg[ \int_{0}^{e^x} \log ( t ) \cos^4 ( t ) \mathrm{d}t \bigg]
\end{align*}$(b)$ For $x > 0 $ define $F ( x ) = \int_{1}^{x} t \log ( t ) \mathrm{d}t . $

$1.$ Determine the open interval(s) (if any) where $F ( x )$ is decreasing and all the open interval(s) (if any) where $F ( x )$ is increasing.

$2.$ Determine all the local minima of $F ( x )$ (if any) and all the local maxima of $F ( x )$ (if any) $.$
7 replies
bubu_2001
Nov 1, 2019
Apple_maths60
an hour ago
9 How many squares do you have memorized
LXC007   79
N an hour ago by ADus
How many squares have you memorized. I have 1-20

Edit: to clarify i mean positive squares from 1 so if you say ten you mean you memorized the squares 1,2,3,4,5,6,7,8,9 and 10
79 replies
LXC007
May 17, 2025
ADus
an hour ago
Annoying Probability Math Problem
RYang2   13
N Apr 18, 2025 by FabulousSpider24
I was working in my math textbook(not the AoPS one) when I came across this math problem:

Determine if the events are dependent or independent.
1. Drawing a red and a blue marble at the same time from a bag containing 6 red and 4 blue marbles
2.(omitted)

I thought it was independent, since the events happen at the same time, but the textbook answer said dependent.
Can someone help me understand(or prove the textbook wrong)?
13 replies
RYang2
Mar 14, 2018
FabulousSpider24
Apr 18, 2025
Annoying Probability Math Problem
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G H BBookmark kLocked kLocked NReply
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RYang2
1936 posts
#1 • 2 Y
Y by Adventure10, Mango247
I was working in my math textbook(not the AoPS one) when I came across this math problem:

Determine if the events are dependent or independent.
1. Drawing a red and a blue marble at the same time from a bag containing 6 red and 4 blue marbles
2.(omitted)

I thought it was independent, since the events happen at the same time, but the textbook answer said dependent.
Can someone help me understand(or prove the textbook wrong)?
This post has been edited 1 time. Last edited by RYang2, Mar 14, 2018, 5:10 PM
Reason: Too general subject
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math_is_life_2004
1374 posts
#2 • 1 Y
Y by Adventure10
It’s dependent
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RYang2
1936 posts
#3 • 1 Y
Y by Adventure10
Explain?
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math_is_life_2004
1374 posts
#4 • 2 Y
Y by Adventure10, Mango247
Actually I think its independent what grade textbook you have?
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brainpopper
1052 posts
#5 • 2 Y
Y by Adventure10, Mango247
Independent is only when they are replace or when the probability doesn't change, right? In #1, If we draw a blue marble first, the probability is 6/10 but the next red marble is 4/9
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RYang2
1936 posts
#6 • 2 Y
Y by Adventure10, Mango247
Pre-Algebra Textbook
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RYang2
1936 posts
#7 • 2 Y
Y by Adventure10, Mango247
And, the problem said at the same time, so there would be no "first" or "second"
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math_is_life_2004
1374 posts
#8 • 2 Y
Y by Adventure10, Mango247
RYang2 wrote:
Pre-Algebra Textbook

Oh I haven’t done that for 2 years. After you memorized the law of cosine you kinda forget everything. #2ndquadraticequation
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creeperhissboom
224 posts
#9 • 2 Y
Y by Adventure10, Mango247
It is dependant.

It is the same as taking one out at a time.
It is only independant if there is replacement.
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A-Username
70 posts
#10 • 2 Y
Y by Adventure10, Mango247
RYang2 wrote:
I was working in my math textbook(not the AoPS one) when I came across this math problem:

Determine if the events are dependent or independent.
1. Drawing a red and a blue marble at the same time from a bag containing 6 red and 4 blue marbles
2.(omitted)

I thought it was independent, since the events happen at the same time, but the textbook answer said dependent.
Can someone help me understand(or prove the textbook wrong)?

@RYang2 Easy explanation for #1 is
Independent-Event 1 doesn't influence Event 2.
Dependent-Event 1 does influence Event 2.
Since this bag contains 6 red and 4 blues, there are 10 marbles in the bag. Now, we know that the color doesn't really matter because we know there is more than 1 for each color. Then we can determine which definition it fits better. First, we know it can't be dependent because if we take it at the same time, there is no sense of order and that the taking of the blue doesn't affect the number of reds there are and vice versa.
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EthanNg6
35 posts
#11
Y by
It's probably dependent
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Jaxman8
122 posts
#12
Y by
I think dependent, if you were to calculate the probabilities for blue first vs red first it’s the same
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giratina3
555 posts
#13 • 1 Y
Y by EthanNg6
The answer is dependent. When you pick 2 marbles, the first pick affects the second one. Although you pick the two at the same time, the change in marble just occurs instantly, so it is still dependent (most average school textbook problem)
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FabulousSpider24
200 posts
#14 • 1 Y
Y by EthanNg6
You can think about it like this: It is dependent because as soon as the first marble is taken, the number of marbles in the bag decreases and so the probability of picking a marble (either red or blue) will change immediately afterwards. .
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