Join our free webinar April 22 to learn about competitive programming!

G
Topic
First Poster
Last Poster
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
[*]April 8th (Math Jam), 4:30pm PT/7:30pm ET, 2025 MATHCOUNTS State Discussion
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.

Introductory: Grades 5-10

Prealgebra 1 Self-Paced

Prealgebra 1
Sunday, Apr 13 - Aug 10
Tuesday, May 13 - Aug 26
Thursday, May 29 - Sep 11
Sunday, Jun 15 - Oct 12
Monday, Jun 30 - Oct 20
Wednesday, Jul 16 - Oct 29

Prealgebra 2 Self-Paced

Prealgebra 2
Sunday, Apr 13 - Aug 10
Wednesday, May 7 - Aug 20
Monday, Jun 2 - Sep 22
Sunday, Jun 29 - Oct 26
Friday, Jul 25 - Nov 21

Introduction to Algebra A Self-Paced

Introduction to Algebra A
Monday, Apr 7 - Jul 28
Sunday, May 11 - Sep 14 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Wednesday, May 14 - Aug 27
Friday, May 30 - Sep 26
Monday, Jun 2 - Sep 22
Sunday, Jun 15 - Oct 12
Thursday, Jun 26 - Oct 9
Tuesday, Jul 15 - Oct 28

Introduction to Counting & Probability Self-Paced

Introduction to Counting & Probability
Wednesday, Apr 16 - Jul 2
Thursday, May 15 - Jul 31
Sunday, Jun 1 - Aug 24
Thursday, Jun 12 - Aug 28
Wednesday, Jul 9 - Sep 24
Sunday, Jul 27 - Oct 19

Introduction to Number Theory
Thursday, Apr 17 - Jul 3
Friday, May 9 - Aug 1
Wednesday, May 21 - Aug 6
Monday, Jun 9 - Aug 25
Sunday, Jun 15 - Sep 14
Tuesday, Jul 15 - Sep 30

Introduction to Algebra B Self-Paced

Introduction to Algebra B
Wednesday, Apr 16 - Jul 30
Tuesday, May 6 - Aug 19
Wednesday, Jun 4 - Sep 17
Sunday, Jun 22 - Oct 19
Friday, Jul 18 - Nov 14

Introduction to Geometry
Wednesday, Apr 23 - Oct 1
Sunday, May 11 - Nov 9
Tuesday, May 20 - Oct 28
Monday, Jun 16 - Dec 8
Friday, Jun 20 - Jan 9
Sunday, Jun 29 - Jan 11
Monday, Jul 14 - Jan 19

Intermediate: Grades 8-12

Intermediate Algebra
Monday, Apr 21 - Oct 13
Sunday, Jun 1 - Nov 23
Tuesday, Jun 10 - Nov 18
Wednesday, Jun 25 - Dec 10
Sunday, Jul 13 - Jan 18
Thursday, Jul 24 - Jan 22

Intermediate Counting & Probability
Wednesday, May 21 - Sep 17
Sunday, Jun 22 - Nov 2

Intermediate Number Theory
Friday, Apr 11 - Jun 27
Sunday, Jun 1 - Aug 24
Wednesday, Jun 18 - Sep 3

Precalculus
Wednesday, Apr 9 - Sep 3
Friday, May 16 - Oct 24
Sunday, Jun 1 - Nov 9
Monday, Jun 30 - Dec 8

Advanced: Grades 9-12

Olympiad Geometry
Tuesday, Jun 10 - Aug 26

Calculus
Tuesday, May 27 - Nov 11
Wednesday, Jun 25 - Dec 17

Group Theory
Thursday, Jun 12 - Sep 11

Contest Preparation: Grades 6-12

MATHCOUNTS/AMC 8 Basics
Wednesday, Apr 16 - Jul 2
Friday, May 23 - Aug 15
Monday, Jun 2 - Aug 18
Thursday, Jun 12 - Aug 28
Sunday, Jun 22 - Sep 21
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)

MATHCOUNTS/AMC 8 Advanced
Friday, Apr 11 - Jun 27
Sunday, May 11 - Aug 10
Tuesday, May 27 - Aug 12
Wednesday, Jun 11 - Aug 27
Sunday, Jun 22 - Sep 21
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)

AMC 10 Problem Series
Friday, May 9 - Aug 1
Sunday, Jun 1 - Aug 24
Thursday, Jun 12 - Aug 28
Tuesday, Jun 17 - Sep 2
Sunday, Jun 22 - Sep 21 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Monday, Jun 23 - Sep 15
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)

AMC 10 Final Fives
Sunday, May 11 - Jun 8
Tuesday, May 27 - Jun 17
Monday, Jun 30 - Jul 21

AMC 12 Problem Series
Tuesday, May 27 - Aug 12
Thursday, Jun 12 - Aug 28
Sunday, Jun 22 - Sep 21
Wednesday, Aug 6 - Oct 22

AMC 12 Final Fives
Sunday, May 18 - Jun 15

F=ma Problem Series
Wednesday, Jun 11 - Aug 27

WOOT Programs
Visit the pages linked for full schedule details for each of these programs!


MathWOOT Level 1
MathWOOT Level 2
ChemWOOT
CodeWOOT
PhysicsWOOT

Programming

Introduction to Programming with Python
Thursday, May 22 - Aug 7
Sunday, Jun 15 - Sep 14 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Tuesday, Jun 17 - Sep 2
Monday, Jun 30 - Sep 22

Intermediate Programming with Python
Sunday, Jun 1 - Aug 24
Monday, Jun 30 - Sep 22

USACO Bronze Problem Series
Tuesday, May 13 - Jul 29
Sunday, Jun 22 - Sep 1

Physics

Introduction to Physics
Wednesday, May 21 - Aug 6
Sunday, Jun 15 - Sep 14
Monday, Jun 23 - Sep 15

Physics 1: Mechanics
Thursday, May 22 - Oct 30
Monday, Jun 23 - Dec 15

Relativity
Sat & Sun, Apr 26 - Apr 27 (4:00 - 7:00 pm ET/1:00 - 4:00pm PT)
Mon, Tue, Wed & Thurs, Jun 23 - Jun 26 (meets every day of the week!)
0 replies
jlacosta
Apr 2, 2025
0 replies
Inequalities
sqing   6
N 16 minutes ago by sqing
Let $ a,b,c> 0 $ and $ ab+bc+ca\leq  3abc . $ Prove that
$$ a+ b^2+c\leq a^2+ b^3+c^2 $$$$ a+ b^{11}+c\leq a^2+ b^{12}+c^2 $$
6 replies
1 viewing
sqing
2 hours ago
sqing
16 minutes ago
Problem of the Week--The Sleeping Beauty Problem
FiestyTiger82   1
N 21 minutes ago by martianrunner
Put your answers here and discuss!
The Problem
1 reply
FiestyTiger82
an hour ago
martianrunner
21 minutes ago
Inequalities
sqing   4
N 3 hours ago by sqing
Let $ a,b,c $ be real numbers such that $ a^2+b^2+c^2=1. $ Prove that$$ |a-b|+|b-2c|+|c-3a|\leq 5$$$$|a-2b|+|b-3c|+|c-4a|\leq \sqrt{42}$$$$ |a-b|+|b-\frac{11}{10}c|+|c-a|\leq \frac{29}{10}$$
4 replies
sqing
Today at 5:05 AM
sqing
3 hours ago
Inequalities
nhathhuyyp5c   2
N 3 hours ago by pooh123
Let $a, b, c$ be non-negative real numbers such that $a^2 + b^2 + c^2 = 3$. Find the maximum and minimum values of the expression
\[
P = \frac{a}{a^2 + 2} + \frac{b}{b^2 + 2} + \frac{c}{c^2 + 2}.
\]
2 replies
nhathhuyyp5c
Apr 20, 2025
pooh123
3 hours ago
high school math
aothatday   8
N Today at 1:09 AM by EthanNg6
Let $x_n$ be a positive root of the equation $x^n=x^2+x+1$. Prove that the following sequence converges: $n^2(x_n-x_{ n+1})$
8 replies
aothatday
Apr 10, 2025
EthanNg6
Today at 1:09 AM
Why is this series not the Fourier series of some Riemann integrable function
tohill   1
N Yesterday at 11:53 PM by alexheinis
$\sum_{n=1}^{\infty}{\frac{\sin nx}{\sqrt{n}}}$ (0<x<2π)
1 reply
tohill
Yesterday at 8:08 AM
alexheinis
Yesterday at 11:53 PM
Research Opportunity
dinowc   0
Yesterday at 10:17 PM
Hi everyone, my name is William Chang and I'm a second year phd student at UCLA studying applied math. Over the past year, I've mentored many undergraduates at UCLA to finished papers (currently under review) in reinforcement learning (see here. :juggle:)

I'm looking to expand my group (and the topics I'm studying) so if you're interested, please let me know. I would especially encourage you to reach out to me chang314@g.ucla.edu if you like math. :wow:
0 replies
dinowc
Yesterday at 10:17 PM
0 replies
Computational Calculus - SMT 2025
Munmun5   3
N Yesterday at 9:58 PM by alexheinis
Source: SMT 2025
1. Consider the set of all continuous and infinitely differentiable functions $f$ with domain $[0,2025]$ satisfying $$f(0)=0,f'(0)=0,f'(2025)=1$$and $f''$ is strictly increasing on $[0,2025]$ Compute smallest real M such that all functions in this set ,$f(2025)<M$ .
2. Polynomials $$A(x)=ax^3+abx^2-4x-c$$$$B(x)=bx^3+bcx^2-6x-a$$$$C(x)=cx^3+cax^2-9x-b$$have local extrema at $b,c,a$ respectively. find $abc$ . Here $a,b,c$ are constants .
3. Let $R$ be the region in the complex plane enclosed by curve $$f(x)=e^{ix}+e^{2ix}+\frac{e^{3ix}}{3}$$for $0\leq x\leq 2\pi$. Compute perimeter of $R$ .
3 replies
Munmun5
Yesterday at 9:35 AM
alexheinis
Yesterday at 9:58 PM
x^{2s}+x^{2s-1}+...+x+1 irreducible over $F_2$?
khanh20   1
N Yesterday at 6:20 PM by khanh20
With $s\in \mathbb{Z}^+; s\ge 2$, whether or not the polynomial $P(x)=x^{2s}+x^{2s-1}+...+x+1$ irreducible over $F_2$?
1 reply
khanh20
Yesterday at 6:18 PM
khanh20
Yesterday at 6:20 PM
Advice on Statistical Proof
ElectrickyRaikou   0
Yesterday at 6:12 PM
Suppose we are given i.i.d.\ observations $X_i$ from a distribution with probability density function (PDF) $f(x_i \mid \theta)$ for $i = 1, \ldots, n$, where the parameter $\theta$ has a prior distribution with PDF $\pi(\theta)$. Consider the following two approaches to Bayesian updating:

(1) Let $X = (X_1, \ldots, X_n)$ be the complete data vector. Denote the posterior PDF as $\pi(\theta \mid x)$, where $x = (x_1, \ldots, x_n)$, obtained by applying Bayes' rule to the full dataset at once.

(2) Start with prior $\pi_0(\theta) = \pi(\theta)$. For each $i = 1, \ldots, n$, let $\pi_{i-1}(\theta)$ be the current prior and update it using observation $x_i$ to obtain the new posterior:

$$\pi_i(\theta) = \frac{f(x_i \mid \theta) \pi_{i-1}(\theta)}{\int f(x_i \mid \theta) \pi_{i-1}(\theta) \, d\theta}.$$
Are the final posteriors $\pi(\theta \mid x)$ from part (a) and $\pi_n(\theta)$ from part (b) the same? Provide a proof or a counterexample.


Here is the proof I've written:

Proof

Do you guys think this is rigorous enough? What would you change?
0 replies
ElectrickyRaikou
Yesterday at 6:12 PM
0 replies
How to solve this problem
xiangovo   1
N Yesterday at 11:09 AM by loup blanc
Source: website
How many nonzero points are there on x^3y + y^3z + z^3x = 0 over the finite field \mathbb{F}_{5^{18}} up to scaling?
1 reply
xiangovo
Mar 19, 2025
loup blanc
Yesterday at 11:09 AM
Finite solution for x
Rohit-2006   1
N Yesterday at 10:41 AM by Filipjack
$P(t)$ be a non constant polynomial with real coefficients. Prove that the system of simultaneous equations —
$$\int_{0}^{x} P(t)sin t dt =0$$$$\int_{0}^{x}P(t) cos t dt=0$$has finitely many solutions $x$.
1 reply
Rohit-2006
Yesterday at 4:19 AM
Filipjack
Yesterday at 10:41 AM
We know that $\frac{d}{dx}\bigg(\frac{dy}{dx}\bigg)=\frac{d^2 y}{dx^2}.$ Why we
Vulch   1
N Yesterday at 10:28 AM by Aiden-1089
We know that $\frac{d}{dx}\bigg(\frac{dy}{dx}\bigg)=\frac{d^2 y}{dx^2}.$ Why we can't write $\frac{d^2 y}{dx^2}$ as $\frac{d^2 y}{d^2 x^2}?$
1 reply
Vulch
Yesterday at 9:15 AM
Aiden-1089
Yesterday at 10:28 AM
complex analysis
functiono   1
N Yesterday at 9:57 AM by Mathzeus1024
Source: exam
find the real number $a$ such that

$\oint_{|z-i|=1} \frac{dz}{z^2-z+a} =\pi$
1 reply
functiono
Jan 15, 2024
Mathzeus1024
Yesterday at 9:57 AM
Hard system of Equations
William_Mai   10
N Feb 18, 2025 by William_Mai
Find the real solutions of the following system of equations:

$\begin{cases}
x^4 = 3y + 2 \\
y^4 = 3z + 2 \\
z^4 = 3x + 2
\end{cases}$

Source: https://www.facebook.com/share/p/1MrR3u8VTU/
10 replies
William_Mai
Feb 17, 2025
William_Mai
Feb 18, 2025
Hard system of Equations
G H J
G H BBookmark kLocked kLocked NReply
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
William_Mai
19 posts
#1
Y by
Find the real solutions of the following system of equations:

$\begin{cases}
x^4 = 3y + 2 \\
y^4 = 3z + 2 \\
z^4 = 3x + 2
\end{cases}$

Source: https://www.facebook.com/share/p/1MrR3u8VTU/
This post has been edited 1 time. Last edited by William_Mai, Feb 18, 2025, 2:03 AM
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
Mathzeus1024
826 posts
#2
Y by
Two such triplets include $(x,y,z) = (\phi, \phi, \phi); (1-\phi, 1-\phi, 1-\phi)$, where $\phi = \frac{1+\sqrt{5}}{2}$ (the Golden Ratio).
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
nextgen2000
29 posts
#3
Y by
Can we see the proof? Thx!
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
Mathzeus1024
826 posts
#4
Y by
nextgen2000 wrote:
Can we see the proof? Thx!

It's simply a matter of solving $N^4=3N+2$. I'm curious if there are additional triplets (with distinct entries) that also work!
This post has been edited 1 time. Last edited by Mathzeus1024, Feb 17, 2025, 3:32 PM
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
nextgen2000
29 posts
#5
Y by
Yes, I think so, but how we prove that $x=y=z$ for real values, because I can prove this only for positive $x,y,z$.
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
EaZ_Shadow
1230 posts
#6 • 1 Y
Y by Ad112358
nextgen2000 wrote:
Yes, I think so, but how we prove that $x=y=z$ for real values, because I can prove this only for positive $x,y,z$.

Most cyclic system of equations have $x=y=z$ as inequalities i think. So a good motivation is to see how to solve $x^4-3x-2$.
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
William_Mai
19 posts
#7
Y by
But can you prove that this is the ONLY solution where x=y=z
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
nextgen2000
29 posts
#8
Y by
EaZ_Shadow wrote:
nextgen2000 wrote:
Yes, I think so, but how we prove that $x=y=z$ for real values, because I can prove this only for positive $x,y,z$.

Most cyclic system of equations have $x=y=z$ as inequalities i think. So a good motivation is to see how to solve $x^4-3x-2$.

Can I see the details?
This post has been edited 1 time. Last edited by nextgen2000, Feb 18, 2025, 11:22 AM
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
Zok_G8D
1 post
#9
Y by
wlog x=min{x,y,z}
we have z^4>=x^4
therefore 3x>=3y, x>=y so x=y
x^4=y^4 => y=z
so x=y=z so you just have to solve x^4-3x-2=0 which is pretty simple
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
nextgen2000
29 posts
#10
Y by
From z^4>=x^4 result z>x only iff z, x>0
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
William_Mai
19 posts
#11
Y by
Zok_G8D wrote:
wlog x=min{x,y,z}
we have z^4>=x^4
therefore 3x>=3y, x>=y so x=y
x^4=y^4 => y=z
so x=y=z so you just have to solve x^4-3x-2=0 which is pretty simple

This a trap because x maybe x<0 so you cant use that
Z K Y
N Quick Reply
G
H
=
a