Stay ahead of learning milestones! Enroll in a class over the summer!

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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)!

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[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]
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0 replies
jlacosta
Apr 2, 2025
0 replies
Sharing My Solutions for IMO 2023 (All 6 Problems) – Feedback Welcome
Blackhole.LightKing   4
N 2 minutes ago by GreekIdiot
Hi everyone,

I worked through all six problems from the 2023 International Mathematical Olympiad (IMO 2023), and I would like to share my solutions here.

I tried to make the explanations clear and complete, and I also added diagrams for the geometry problems to make them easier to follow.

Topics covered:

Number Theory

Geometry

Algebra

Combinatorics

You can find the full solution PDF attached (or linked below).

https://agi-origin.ai/assets/pdf/AGI-Origin_IMO_2023_Solution.pdf

I’m still learning, so if you see any mistakes, unclear parts, or better ways to explain things, I would really appreciate your feedback!

Thank you for reading, and I hope this can be helpful to others who are studying IMO problems too
4 replies
Blackhole.LightKing
22 minutes ago
GreekIdiot
2 minutes ago
System of two diophantine equations
AlastorMoody   4
N 3 minutes ago by MATHS_ENTUSIAST
Source: Balkan MO ShortList 2007 N1
Solve the given system in prime numbers
\begin{align*} x^2+yu = (x+u)^v \end{align*}\begin{align*} x^2+yz=u^4 \end{align*}
4 replies
AlastorMoody
Apr 6, 2020
MATHS_ENTUSIAST
3 minutes ago
A bash problem
kjhgyuio   1
N 4 minutes ago by zhoujef000
........
1 reply
1 viewing
kjhgyuio
23 minutes ago
zhoujef000
4 minutes ago
Minimum term of n^m
Kunihiko_Chikaya   1
N 5 minutes ago by Mathzeus1024
Source: 19?? Mie University entrance exam
For any two positive integers $ m,\ n\ (m\geq 2)$, suppose that $ n^m$ is expressed by the sum of $ n$ consecutive odd numbers. Express the minimum term in terms of $ n$ and $ m$.
1 reply
Kunihiko_Chikaya
Jan 28, 2010
Mathzeus1024
5 minutes ago
Double Sum
P162008   1
N 2 hours ago by alexheinis
Let $\xi = \lim_{m \to\infty} \sum_{n=4}^{m} \sum_{k=2}^{n-2} \frac{1}{\binom{n}{k}}.$ If the value of $\xi$ can be written as $\frac{m}{n}$ where $m$ and $n$ are co-prime positive integers then compute the value of $m^3 + n^3.$
1 reply
P162008
Today at 3:22 AM
alexheinis
2 hours ago
Newton's Sum
P162008   3
N 2 hours ago by lbh_qys
If $\sum_{cyc} a = 7, \sum_{cyc} a^2 = 15, \sum_{cyc} a^3 = 19$ and $\sum_{cyc} a^4 = 25$ where each summation runs over $4$ variables $a,b,c$ and $d.$ Then find the value of $\sum_{cyc} a^5.$
3 replies
P162008
Today at 1:51 AM
lbh_qys
2 hours ago
A nice inequality
KhuongTrang   0
4 hours ago
[quote=KhuongTrang]Problem. Let $a,b,c\ge 0: ab+bc+ca>0.$ Prove that$$\color{blue}{\frac{\left(2ab+ca+cb\right)^{2}}{a^{2}+4ab+b^{2}}+\frac{\left(2bc+ab+ac\right)^{2}}{b^{2}+4bc+c^{2}}+\frac{\left(2ca+bc+ba\right)^{2}}{c^{2}+4ca+a^{2}}\ge \frac{8(ab+bc+ca)}{3}.}$$[/quote]

0 replies
KhuongTrang
4 hours ago
0 replies
Inequalities from SXTX
sqing   20
N 5 hours ago by sqing
T702. Let $ a,b,c>0 $ and $ a+2b+3c=\sqrt{13}. $ Prove that $$ \sqrt{a^2+1} +2\sqrt{b^2+1} +3\sqrt{c^2+1} \geq 7$$S
T703. Let $ a,b $ be real numbers such that $ a+b\neq 0. $. Find the minimum of $ a^2+b^2+(\frac{1-ab}{a+b} )^2.$
T704. Let $ a,b,c>0 $ and $ a+b+c=3. $ Prove that $$ \frac{a^2+7}{(c+a)(a+b)} + \frac{b^2+7}{(a+b)(b+c)} +\frac{c^2+7}{(b+c)(c+a)}  \geq 6$$S
20 replies
1 viewing
sqing
Feb 18, 2025
sqing
5 hours ago
Theory of Equations
P162008   3
N 6 hours ago by P162008
Let $a,b,c,d$ and $e\in [-2,2]$ such that $\sum_{cyc} a = 0, \sum_{cyc} a^3 = 0, \sum_{cyc} a^5 = 10.$ Find the value of $\sum_{cyc} a^2.$
3 replies
P162008
Apr 23, 2025
P162008
6 hours ago
Fun & Simple puzzle
Kscv   7
N 6 hours ago by vanstraelen
$\angle DCA=45^{\circ},$ $\angle BDC=15^{\circ},$ $\overline{AC}=\overline{CB}$

$\angle ADC=?$
7 replies
1 viewing
Kscv
Apr 13, 2025
vanstraelen
6 hours ago
A problem involving modulus from JEE coaching
AshAuktober   7
N Today at 5:55 AM by Jhonyboy
Solve over $\mathbb{R}$:
$$|x-1|+|x+2| = 3x.$$
(There are two ways to do this, one being bashing out cases. Try to find the other.)
7 replies
AshAuktober
Apr 21, 2025
Jhonyboy
Today at 5:55 AM
FB = BK , circumcircle and altitude related (In the World of Mathematics 516)
parmenides51   5
N Today at 4:05 AM by jasperE3
Let $BT$ be the altitude and $H$ be the intersection point of the altitudes of triangle $ABC$. Point $N$ is symmetric to $H$ with respect to $BC$. The circumcircle of triangle $ATN$ intersects $BC$ at points $F$ and $K$. Prove that $FB = BK$.

(V. Starodub, Kyiv)
5 replies
parmenides51
Apr 19, 2020
jasperE3
Today at 4:05 AM
Polynomial Limit
P162008   0
Today at 1:47 AM
Let $p = \lim_{y\to\infty} \left(\frac{2}{y^2} \left(\lim_{z\to\infty} \frac{1}{z^4} \left(\lim_{x\to\infty} \frac{((y^2 + y + 1)x^k + 1)^{z^2 + z + 1} - ((z^2 + z + 1)x^k + 1)^{y^2 + y + 1}}{x^{2k}}\right)\right)\right)^y$ where $k \in N$ and $q = \lim_{n\to\infty} \left(\frac{\binom{2n}{n}. n!}{n^n}\right)^{1/n}$ where $n \in N$. Find the value of $p.q.$
0 replies
P162008
Today at 1:47 AM
0 replies
Octagon Problem
Shiyul   4
N Today at 1:43 AM by Sid-darth-vater
The vertices of octagon $ABCDEFGH$ lie on the same circle. If $AB = BC = CD = DE = 11$ and $EF = FG = GH = HA = sqrt2$, what is the area of octagon $ABCDEFGH$?

I approached this problem by noticing that the area of the octagon is the area of the eight isoceles triangles with lengths $r$, $r$, and $sqrt2$ or 11. However, I didn't know how to find the radius. Can anyone give me a hint?
4 replies
Shiyul
Yesterday at 11:41 PM
Sid-darth-vater
Today at 1:43 AM
4 circles, tangent in many ways, r_1+r_2+r_3=r
parmenides51   0
Jun 15, 2020
Source: 2002 Argentina OMA L3 p3
In a circumference $\Gamma$ a chord $PQ$ is considered such that the segment that joins the midpoint of the smallest arc $PQ$ and the midpoint of the segment $PQ$ measures $1$. Let $\Gamma_1, \Gamma_2$ and $\Gamma_3$ be three tangent circumferences to the chord $PQ$ that are in the same half plane than the center of $\Gamma$ with respect to the line $PQ$. Furthermore, $\Gamma_1$ and $\Gamma_3$ are internally tangent to $\Gamma$ and externally tangent to$ \Gamma_2$, and the centers of $\Gamma_1$ and $\Gamma_3$ are on different halfplanes with respect to the line determined by the centers of $\Gamma$ and $\Gamma_2$.
If the sum of the radii of $\Gamma_1, \Gamma_2$ and $\Gamma_3$ is equal to the radius of $\Gamma$, calculate the radius of $\Gamma_2$.
0 replies
parmenides51
Jun 15, 2020
0 replies
4 circles, tangent in many ways, r_1+r_2+r_3=r
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Source: 2002 Argentina OMA L3 p3
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parmenides51
30631 posts
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In a circumference $\Gamma$ a chord $PQ$ is considered such that the segment that joins the midpoint of the smallest arc $PQ$ and the midpoint of the segment $PQ$ measures $1$. Let $\Gamma_1, \Gamma_2$ and $\Gamma_3$ be three tangent circumferences to the chord $PQ$ that are in the same half plane than the center of $\Gamma$ with respect to the line $PQ$. Furthermore, $\Gamma_1$ and $\Gamma_3$ are internally tangent to $\Gamma$ and externally tangent to$ \Gamma_2$, and the centers of $\Gamma_1$ and $\Gamma_3$ are on different halfplanes with respect to the line determined by the centers of $\Gamma$ and $\Gamma_2$.
If the sum of the radii of $\Gamma_1, \Gamma_2$ and $\Gamma_3$ is equal to the radius of $\Gamma$, calculate the radius of $\Gamma_2$.
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