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k a July Highlights and 2025 AoPS Online Class Information
jwelsh   0
Jul 1, 2025
We are halfway through summer, so be sure to carve out some time to keep your skills sharp and explore challenging topics at AoPS Online and our AoPS Academies (including the Virtual Campus)!

[list][*]Over 60 summer classes are starting at the Virtual Campus on July 7th - check out the math and language arts options for middle through high school levels.
[*]At AoPS Online, we have accelerated sections where you can complete a course in half the time by meeting twice/week instead of once/week, starting on July 8th:
[list][*]MATHCOUNTS/AMC 8 Basics
[*]MATHCOUNTS/AMC 8 Advanced
[*]AMC Problem Series[/list]
[*]Plus, AoPS Online has a special seminar July 14 - 17 that is outside the standard fare: Paradoxes and Infinity
[*]We are expanding our in-person AoPS Academy locations - are you looking for a strong community of problem solvers, exemplary instruction, and math and language arts options? Look to see if we have a location near you and enroll in summer camps or academic year classes today! New locations include campuses in California, Georgia, New York, Illinois, and Oregon and more coming soon![/list]

MOP (Math Olympiad Summer Program) just ended and the IMO (International Mathematical Olympiad) is right around the corner! This year’s IMO will be held in Australia, July 10th - 20th. Congratulations to all the MOP students for reaching this incredible level and best of luck to all selected to represent their countries at this year’s IMO! Did you know that, in the last 10 years, 59 USA International Math Olympiad team members have medaled and have taken over 360 AoPS Online courses. Take advantage of our Worldwide Online Olympiad Training (WOOT) courses
and train with the best! Please note that early bird pricing ends August 19th!
Are you tired of the heat and thinking about Fall? You can plan your Fall schedule now with classes at either AoPS Online, AoPS Academy Virtual Campus, or one of our AoPS Academies around the US.

Our full course list for upcoming classes is below:
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0 replies
jwelsh
Jul 1, 2025
0 replies
My First Math Tournament
dragnin   25
N 21 minutes ago by douqile
I'm back with a 2nd math story! :jump: Do you remember your first math competition? Was it scary? :noo: Did you brag a lot after it even though you were probably not as smart as you say? :flex: I think we all improved a lot since then! :icecream:
Click to reveal hidden text
Epilogue:
Click to reveal hidden text

Here is my other story if anyone is interested: https://artofproblemsolving.com/community/c3t968896f3h2640331_the_best_day_of_my_life_so_far_an_inspiring_story

Thank you for reading!

25 replies
dragnin
Sep 12, 2021
douqile
21 minutes ago
New AOPS videos?!
Owinner   43
N 36 minutes ago by douqile
I just saw on Art Of Problem Solving's youtube channel new videos made by Richard, and I assume this is for Intro to Algebra B. Am I the only one who just saw this?
43 replies
Owinner
Jan 26, 2025
douqile
36 minutes ago
2024 NYMA = New Years Mock AIME #10 complex ineq
parmenides51   3
N an hour ago by douqile
Two complex numbers $z_1$ and $z_2$ are chosen uniformly and at random from the disk $0\le |z| \le 1$. Suppose $z_1 = a + bi$ and $z_2 = c + di$, where $a, b, c, d$ are all real numbers. The probability that
$$\frac{a^2 + b^2} {2abcd + a^2c^2 + b^2d^2} \le  \frac{a^2 + b^2}{ - 2abcd + a^2d^2 + b^2c^2} \le  4$$can be written as $\frac{p+q\pi -r\sqrt{s}}{ i \pi}$ , where $p, q, r, s, t$ are positive integers, gcd $(p, q, r, t) =1$, and $s$ is not divisible by the square of any prime. Compute $pqrst$.
3 replies
parmenides51
Feb 13, 2024
douqile
an hour ago
AIMO 2025 olympiad
Unknown0108   1
N an hour ago by Unknown0108
If you are participating in Asia International olympiad 2025 can we share our knowledge cuz I am participating too
1 reply
Unknown0108
Jul 29, 2025
Unknown0108
an hour ago
Perfect square
Ecrin_eren   3
N 2 hours ago by Solar Plexsus


Find all integer values of n such that for every pair of integers (a, b) satisfying:

n·a² + a = (n + 1)·b² + b

the number |a − b| is always a perfect square.




3 replies
Ecrin_eren
Jul 28, 2025
Solar Plexsus
2 hours ago
integer solution
aria123   0
2 hours ago
Find all integer solutions of the equation $x^2+xy+3y^2=x^2y^2$
0 replies
aria123
2 hours ago
0 replies
1998 St. Petersburg
radioactiverascal90210   0
2 hours ago
In the plane are given several squares with parallel sides, such that among any $n$ of them, there exist four having a common point. Prove that the squares can be divided into at most $n$$3$ groups, such that
all of the squares in a group have a common point.
0 replies
radioactiverascal90210
2 hours ago
0 replies
Inequality proof
radioactiverascal90210   0
2 hours ago
There are $n$ points $P_1$, $P_2$ . . . , $P_n$ in the interval $[-1,1]$ where the
points are consecutively arranged from left to right. Let $a_i$ be the product of all
distances from $P_i$ to the other $n$$1$ points. Prove that
$\sum_{i=1}^n$ $\frac{1}{a_i}$ $\ge$ $2^{n-1}$
0 replies
radioactiverascal90210
2 hours ago
0 replies
A little fun,
AlexCenteno2007   19
N 4 hours ago by AlexCenteno2007
Let ABCD be a trapeze with AD ∥ BC. M and N are the midpoints of CD and BC
respectively, and P is the common point of the lines AM and DN. If PM/AP = 4, show that
ABCD is a parallelogram.
19 replies
AlexCenteno2007
Jul 22, 2025
AlexCenteno2007
4 hours ago
If OAB and OAC share equal angles and sides, why aren't they congruent?
Merkane   0
Today at 4:33 AM

Problem 1.39 (CGMO 2012/5). Let ABC be a triangle. The incircle of ABC is tangent
to AB and AC at D and E respectively. Let O denote the circumcenter of BCI .
Prove that ∠ODB = ∠OEC. Hints: 643 89 Sol: p.241

While I have solved the problem, I encountered a step that seems logically sound but leads to a contradiction, and I would like help identifying the flaw.

Here is the reasoning I followed:

The quadrilateral ABOC is cyclic.

OB = OC.

∠OAB = ∠OCB.
Similarly, ∠OAC = ∠OBC.

From symmetry and the above, it seems that ∠OAB = ∠OAC.

Since OA is a shared side, I concluded that triangle OAB ≅ triangle OAC.


But clearly, OAB and OAC are not congruent.
Where exactly is the logical error in this argument?
0 replies
Merkane
Today at 4:33 AM
0 replies
Geometry Problem
Rice_Farmer   0
Today at 3:09 AM
Let $w_1$ ad $w_2$ be two circles intersecting at $P$ and $Q.$ The tangent like closer to $Q$ touches $w_1$ and $w_2$ at $M$ and $N$ respectively. If $PQ=3,NQ=2,$ and $MN=PN,$ find $QM.$
0 replies
1 viewing
Rice_Farmer
Today at 3:09 AM
0 replies
A writing game
Ecrin_eren   2
N Today at 1:51 AM by Ecrin_eren


There is an integer greater than 1 written on the board in A’s house. Every morning when A wakes up, he erases the number n on the board and does the following:

If there is a positive integer m such that m^3= n, then he writes m on the board.

Otherwise, he writes 2n+1 on the board.


Since A repeats this process infinitely many times, prove that among all the numbers A has written and will write on the board, there are infinitely many greater than 10^100.





2 replies
Ecrin_eren
Jul 28, 2025
Ecrin_eren
Today at 1:51 AM
Inequalities
sqing   11
N Today at 1:47 AM by sqing
Let $ a,b,c\geq 0, \frac{1}{1+a}+\frac{1}{1+b}+\frac{1}{1+c}=\frac{3}{2}.$ Prove that
$$ \left(a+b+c-\frac{17}{6}\right)^2+9abc   \geq\frac{325}{36}$$$$   \left(a+b+c-\frac{5}{2}\right)^2+12abc \geq\frac{49}{4}$$$$\left(a+b+c-\frac{14}{5}\right)^2+\frac{49}{5}abc \geq\frac{49}{5}$$
11 replies
sqing
Jun 30, 2025
sqing
Today at 1:47 AM
Inequalities
sqing   8
N Today at 1:22 AM by sqing
Let $ a,b> 0, a^2+b^2+ab=3 .$ Prove that
$$ (a+b+1)^2(\frac {a} {b^2+1}+\frac {b} {a^2+1})\geq 9$$Let $ a,b> 0, a+b+ab=3 .$ Prove that
$$(a+b+1)^2(\frac {a+1} {b^2+1}+\frac {b+1} {a^2+1})\geq 18$$Let $ a,b> 0, a+b+2ab=4.$ Prove that
$$(a+b+1)^2(\frac {a} {b^2+1}+\frac {b} {a^2+1})\geq 9$$$$ (a+b+1)^2(\frac {a+1} {b^2+1}+\frac {b+1} {a^2+1}) \geq 18$$
8 replies
sqing
Jul 25, 2025
sqing
Today at 1:22 AM
Personal Modulo Problem (Title: Encrypted Code)
PikaVee   2
N Jun 5, 2025 by Yihangzh
3 Pokemon each have they own number to use on a part of a lock. Star the Pikachu has the number 87, Luna the Eevee has the number 92, and Aero the Mew has the number 79. A part of their code is found in the expression $C \equiv (3S+5L-2A) \bmod 101$.

To double check if it is right then it needs to follow $C \equiv 5 \bmod 8$ and $C \equiv 3 \bmod 11$. If it does follow it then you need to find the sum of the coefficients with the code the code itself, but if not replace the sum of the coefficients with the lowest possible sum of coefficients where $X+Y+Z+C$ in $(XZ+YL-ZA) \bmod 101$ where X, Y, and Z are positive integers more than 0.

Solution
2 replies
PikaVee
Jun 4, 2025
Yihangzh
Jun 5, 2025
Personal Modulo Problem (Title: Encrypted Code)
G H J
G H BBookmark kLocked kLocked NReply
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PikaVee
22 posts
#1
Y by
3 Pokemon each have they own number to use on a part of a lock. Star the Pikachu has the number 87, Luna the Eevee has the number 92, and Aero the Mew has the number 79. A part of their code is found in the expression $C \equiv (3S+5L-2A) \bmod 101$.

To double check if it is right then it needs to follow $C \equiv 5 \bmod 8$ and $C \equiv 3 \bmod 11$. If it does follow it then you need to find the sum of the coefficients with the code the code itself, but if not replace the sum of the coefficients with the lowest possible sum of coefficients where $X+Y+Z+C$ in $(XZ+YL-ZA) \bmod 101$ where X, Y, and Z are positive integers more than 0.

Solution
Z K Y
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Yihangzh
1551 posts
#2
Y by
Solution
Z K Y
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Yihangzh
1551 posts
#3
Y by
Yihangzh wrote:
Solution

oof, I'm so dumb, just realized my mistake
Z K Y
N Quick Reply
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