#competition-math
1 messages · Page 38 of 1
If anyone from India, are these online classes from Unacademy, PW, etc. enough for Jee Mains if you study well from your side? I have no experience of it so I am just thinking if online or offline classes will be better.
No too old
pray that the 13 year old who replies to this won't drive you insane
guess who??? 😜
Does anyone have any tips for taking the Putnam exam other than learning the material more and practicing questions
Does anyone know any free textbooks that could help me on the AMC10?
i heard that like coffin problems are similar to this
they were created to prevent jewish students from entering universities or mshtg
Last tuesday i experienced the unfairest experience i have ever had on olympiads, you see, i went to a very recognized school on my city to participate in olympiads , so, i go and get presented the next problem: On the sucession: 8,2,-4,-10... determine if 132 is part of the sucession. first thing i do is check if 132 is a 6 multiple , and turns out that it was, so i said yes and they said that was not the solution, so i try to do all the terms until 132, but no, the guy that was checking on the participants take my paper out of my hands and tells me that my solution needs to be checked by organizers, the thing is that i had 180 seconds to solve, by the time the paper was brought back to me i got 30 seconds and got to do until 112 and time finished. Note that this is supposed to be 10th grade (Colombian 9th grade) olympiads where i saw 8th grade problems. Opinions on this? What could i do to participate on TRUE experiences of olympiads?
132 is not part of the sequence tho? The sequence is of numbers two more than a multiple of 6, right?
Anyways, the succession is going the wrong way so even if it were 12, 6, 0, -6, 132 wouldn't show up iirc
Thats what i realized, so decided to write all the terms on the sucession, the thing is that even tho evaluator told me the thing was wrong he took my paper no reason at all
Oh dang
I've never really done a math Olympiad before but that sounds infuriating
yeah it was
Can anyone coach me on competitive math problems?
this is not the place to ask for that
It's the competition math channel, no?
we don't offer tutoring on this server
if you have a specific comp maths problem you would like help with, you can just post it here
oh ok, thanks for the clarification
What's 1÷0?
That doesn't produce a result.
Divisions with 0 in the denominator do not have a defined meaning.
does IMO or AMO have varying tests for different grades?
limit positive x-> 0 1/x is infinity
They didn't ask about a limit, though.
That's the mistake most people does
Yupp
JMO is for people who qualified through amc 10
but no, IMO and AMO are the same for all grades
Bro why you sending ts here
i think it was a bot lol
lol
I see this channel dedicated for competetion maths so can can anyone tell me resources from here I can prepare for Maths olympiad?
Is it 334?
What is it
The bottom equation is the first minus thrice the second plus thrice the third I think
yea
how does one just see this
you can find the difference between 1st and 2nd equation
then the same for 2nd and 3rd
you get 3x + 5x + 7x + 9x + 11x + 13x + 15x and 5x + 7x + 9x + 11x + 13x + 15x + 17x
the difference between them is 2x + 2x + 2x + 2x + 2x + 2x + 2x
adding that to 3rd gives final equation
Note that (n+3)² is linearly dependent on (n+2)²,(n+1)²,n²
Also I hoped the three equations were linearly dependent and they were!
basically finite differences on the sequence n^2 if ur familiar with it
You can row reduce the. Use the first 2 factors to determine the right linear combination
Do L2 <- L2 - 4 L1
L3 <- L3 - 9L1
etc.
My approach was trying to make 100 with plus or minus 49, 64 and 81. The other stuff just works out then.
no bot bro 😭
im out of idea for this problem ive been thinking it for like 2 days
They were not talking about you. Someone else whose post was deleted.
yeah there was a scam that was deleted
There are better ways of thinking but if can’t see it then can always do the algebra until it gets clearer
or like this
to be blunt: if you need to ask that question you’re not ready to do IMO level problems
start by learning about the qualification process from your country
what contests do you need to do to enter the qualification process?
study for those, do well enough to advance, repeat
Hello
hello
are aops volumes 1 and 2 good for training competition math at a middle school level (like mathcounts, amc 8 and 10, MOAA, and other things like math kangaroo)?
they’re very outdated compared to modern resources, supplement with actual recent contest problems
oh
is mathdash good?
I have no idea what that is
haven’t looked at middle school level stuff in at least 7 years
oh
mathdash is like a practice platform thing
don’t restrict yourself just to one platform
as long as you’re practicing on challenging problems you’ll be improving your skills
yeah but im a lazy person
so
yeah
It’s not as good as it used to be
there’s a decent amount of ai slop and the educative material is mid
If you want to do the contests feel free to do them but there’s better options for an educational experience
is there anyone who got a good score on the amc 10 or 12 who can help me study
they are good, but the best option is just to grind past year tests
oh
Can help with questions and concepts
how much have u gotten on practice tests
Umm last time I took it I got 76 ish
I HAVE BEEN BEATING MY HEAD AGAINST THE FUCKING WALL, AT THESE GOD DAMN MOTHERFUCKING ALCUMUS PROBLEMS FOR 2 GOD DAMN HOURS! IT MAKES NO FUCKING SENSE! ITS ALL SO FUCKING STUPID GOD DAMN IT! WHAT THE FUCK DO THESE STUPID FUCKING ASSHOLE BITCHES WANT ME TO DO!!!!!!!!!
FUCKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK
💔
Bro chill the fuck out
secret achievement “ragequit”: leave alcumus for 12 hours after getting a problem wrong
I didn’t get “ a question wrong” I got 80 questions wrong
80 😭
uhh can anyone tell me about incho ? ive heard about it before as im preparing for JEE but have no idea on what it actually is
like whats the level of it
idt 76 is a possible score bro
what defines a good score
DHR?
Are there any tricks, or not-well known formulas for conic sections that anybody can slide my way? Im doing an Oral presentation contest for the North Suburban Math League in illinois and our topic is Conic sections from AoPs Intermediate Algebra Chapter 5
ima be real wit u
the most important part is solving problems and getting consistent (fewer sillies)
if u want i can add u to the IL math discord
yes pls
check dms
how to get gud at amc 12 fr 💔
Can anybody help me with gmat exam..i haven't started anything and didn't touch math for 2 yr
What's the syllabus
Data Sufficiency
Data Analysis (graphs, charts, tables)
Multi-source reasoning
Two-part analysis (quant + verbal mix)
Statistics & probability applications
Arithmetic (percentages, ratios, fractions, averages, profit-loss, simple & compound interest, speed-distance-time, work-time, number properties, etc.)
Algebra (linear equations, quadratic equations, inequalities, functions)
Word problems
Geometry basics (lines, angles, triangles, circles, coordinate geometry)
Statistics basics (mean, median, mode, standard deviation, probability, permutations & combinations)
I can help with doubt solving
Of syllabus later to statistics
Ok thanks ..can i ask doubt on personal chat?
I can help with algebra, geometry and some parts of statistics
How
It id physically impossible to get a 76 💀
You didn’t get a 76 vro 💔
Bro give the actual score
6 x correct + 0 incorrect + 1.5 x skip
what do they mean by this what is it specifically
are they referring to method of differences for summations?
Difference equations are like x_n+1 = x_n + a
Or something like x_n+1= x_n + ax_n
Or something similar
So basically it's a equation which relates one term of a sequence with another
is that not just a recurrence relation
Me too, I had to google it to be sure. I had forgotten that such a thing exists
Hellow
NIce to meet you
yep
I'm sorry interrupt you.
?
I am a university student, and I came here first.
can you help me?
I don't know about here, well
With what topic
Ok
anything about here
yep
And some smartass ppl answer them
ya
!
Talk to ppl
ppl? So sorry,What is it?
People
oha. sorry.
Bruhh.
Got any doubts related to concepts in maths , question solving shoot!
Don't call me, just ping me
sorry
I see.
Is happy smile ur name
It's too my nickname.
Where have you gone?
Busy
why?
organic chemistry
studying? now
Yep
Studying
Ok.
Self study
Good
Byee
👍

Chat in dm dude or in #discussion
I don't know it
Bot ahhh
Bro I told you not to chat here
Unfortunately I cant join the math competition in the college and im f-king upset AAAAAA
Cuz i finished all math class
But I have still 3 years of college left
I think I got the tech , to get ready in time. I have very little studying done but if I do 2 AoPS chapters a day 17 alcumus sections a day starting from the very start I have a full 17 days I can spend fully on doing real past AMC 10 problems and watching old videos reviewing full past exams
Can I make it
olympiad people, help me solve this
On line l, points A and B are placed, and on line S parallel to it, points C1, C2, ..., are placed in order. Find the total number of triangles formed inside the trapezoid by connecting these points in all possible ways.
Probably reposted? #help-3 message
yep no one figured it out
in the future, please be considerate and don't repost in multiple channels
cause it can lead to helpers double answering, which is inconsiderate of their time
Got it
Let's see who is able to solve this problem.
The price of a gem is proportional to the square of its weight. Prove that the maximum depreciation occurs if we split it in half.
One fraction of the gem is x so the other part is 1-x
The price is proportional to (1-x)^2
This is minimized when x=1/2 by parabola
QED
Olympiad level proof trust
You could first connect all the C points to A
I assume the trapezoid is the largest quadrilateral that can be formed using the points?
Then, when connecting C points to B, it creates a new triangle, and extra ones for each intersection
I would guess so
Each line to B intersects with one fewer line to A as you draw the lines, or something to that effect
Trying smaller cases is probably the easiest way
Has anyone here taken the octm and if so, what was the difficulty of the matrix probs on it
Dont say answees obviously, i just want to know how much i should focus on them
does anyone wanna join my server?
Whats it abt
This is not correct at any time you have justified how it can be that the price is proportional to the weight ^2. If the minimum price of the maximum were split in half
A hint, this is an optimization problem.
Problem to solve is this
what does depreciation mean here?
The minimum price
ohh
Isn't this a simple calculus problem? We need to prove that the minimum of x^2 + (1-x)^2 is at the point x = 0.5, which can be simply found by taking the derivative and setting it to 0
Indeed!!
But x is not equal to 0.5, don't put that equal, it's false. They put 0.5 so you can verify that value.
And not even x = 0.5
So, solve it well
It's even simpler to notice that the depreciation will be a polynomial of degree at most 2 (you don't need to actually find the coefficients) with f(0)=f(1)=0 and f(½) =½>0, so it must be a parabola with a maximim at the apex. And the apex of the parabola is midway between its roots, which we already know are 0 and 1.
(Assuming, as we need to for the problem to make sense, that we're implicitly supposed to cut the gem into two pieces. If there can be more than two, the specified conclusion is not even true -- we can approach a depreciation of 100% by grinding the gem into dust...)
I have about less than a month before like an invitational math contest, I have a bit of backgrounds working with comp math, should I just grind out the questions of past papers or is there something better to do
<@&268886789983436800> spam bot
Let number of points in line S = n
Case 1: Top vertex on line l
Number of triangles
= C(n,2) * 2
= n!/(2!(n-2)!) * 2
= n(n-1)/2 * 2
= n(n-1)
= n²-n
Case 2: Top vertex on line S
Number of triangles = n
Case 3: Intersecting lines
Fix the 2 points on line l
Pick 2 points on line S
Each results in 2 triangles
Number of triangles = C(n,2) * 2 = n²-n
Total number of triangles
= (n²-n) + n + (n²-n)
= 2n² - n
= n(2n - 1)
Is it 4
number of ways of selecting 3 points out of 4
@feral drift is this correct?
which book is best for olympiad math?
challanges and thrills of precollege mathematics 4th editon book and mathematical Circles Russian editon?
how to sign up for amc 8
Really depends on your level. Overall, I think no book is the best for all Olympiad math, but some are really good for certain topics. For example, the best geometry book will most likely not talk about ROUF, etc.. overall, start with aops, then go deeper into a certain subject
look at basic olympiad notes introducing concepts and easy problems and work from there
don’t have my school
you do not want to be in the southeast
if your school offers it take it through there
otherwise if u live in a decently populated place there should be a local testing center
yo is the P(n) approximately 1/(4n *sqrt(3) *exp(pi (sqrt(2n/3))
real?
I found it off the movie
Honestly, both options are good, but most people I know prefer the challenges and thrills of pre-college math.
I have one piece of advice: If you choose the book "Pathfinder to Olympiad Mathematics, 1st Edition" by V. Seshan and Vikash, you won’t need to look for any other books. It’s my favorite! It contains a good number of solved examples and many useful tricks, along with hundreds of questions from real Olympiads.
ok honestly CATOPM is the good one as it have many exercises over 1500+ smthing so!
Thanks, as also this is not the channel for book discussion so maybe u understand!
Does it countain complex numbers problems or algebra
how would i find it
if u cant find it ask local colleges and universities
very natural way to solve such problems is to set them up on complex plane let the center of the circle, $O$, be the origin of the complex plane, so $O$ corresponds to the complex number $0$. Let the vertex $A_1$ lie on the positive real axis. Since it is on the circle of radius $R$, its coordinate is the real number $R$.
The vertices $A_1, A_2, \dots, A_n$ form a regular $n$-gon inscribed in this circle then they can be represented by the $n$-th roots of $R^n$. The complex number corresponding to vertex $A_k$ is therefore given by:
$$ a_k = R e^{i \frac{2\pi (k-1)}{n}} \quad \text{for } k = 1, 2, \dots, n $$
These $n$ values are precisely the roots of the polynomial equation $z^n - R^n = 0$.
The point $P$ lies on the line segment $OA_1$ extended beyond $A_1$. Since $O$ is the origin and $A_1$ is at $R$ on the real axis, $P$ must also lie on the positive real axis. Let its coordinate be the real number $p$. The condition "extended beyond $A_1$" means that the distance $OP$ is greater than the distance $OA_1$. Thus, we have $p > R$. the distance $OP$ is simply $|p| = p$
recognizing the product might be helpful here $\prod_{k=1}^{n} (p - a_k)$. since the complex numbers $a_1, a_2, \dots, an$ are the roots of the polynomial $z^n - R^n$, we can express this polynomial in its factored form:
$$ z^n - R^n = \prod{k=1}^{n} (z - ak) $$
This identity holds for any complex number $z$. maybe then we can therefore evaluate it at our specific point $z=p$:
$$ p^n - R^n = \prod{k=1}^{n} (p - a_k) $$ this much takes u very far in proving final thing u can move from here easily ig
many putnam problems r often repetitive in structure or ideas i have seen such problems like lot of times
I'm going into my highschool's math team!
What’s a fast way to solve 2011^2011
- don’t
Im mostly trying to look for patterns but nothing seems to work
Oh sorry
its value mod some number?
I meant hundreds digit lol
you could reduce the exponent a fair bit with Euler totient
and use similar tricks to try to reduce it to smth you can compute relatively easily
Alr I’ll try again.
Hey guys, im a junior oding amc 12, and I took the amc 12 a 2025 just now and got 64.5. Is it possible for me to qualify for aime with one moneth left
- spelling
- if you’re that far off cutoff when mocking it’s highly unlikely
2011^2011 = 11^2011 = 11^11 = (10+1)^11 = 10^2 * 11c2 + 10^1*11c1 + 1 = 5500+110+1 = 611 (mod 1000)
using fact that 11^phi(1000) = 1 (mod 1000)
guys im cooked for SMC could someone pls help me
like helping me through past paper question and particularly logic
Orz Mopper
Would his be a “hard” question on amc 10
Bro what
Probably no because it uses standard topics without any other critical thinking
in fact, Euler's totient theorem is not even needed
I didn’t even know what that was lol 😭
(10 + 1)^2011 = 1 + 10 * 2011 + 100 * 2011 * 2010/2 + 1000 * ....
= 1 + 10 * 11 + 100 * (units digit 5)
(mod 1000)
yeah, so the idea was that you use Euler's theorem
the only prime factors of 1000 are 2 and 5, so phi(1000) = 1000 * (1 - 1/2) * (1 - 1/5) = 400
don't even think about that
consider that there are 3 terms before you get multiplication by 10^3, 10^4 and so on
That’s smart
yeah it is just the binomial theorem
of course there's some level of depth needed to answer it
Lowkey binomial theorem is way better instead of finding patterns
Like hundreds or thousands digit
there's also Hensel's lifting lemma that can be used for other problems where 1000 etc is also composite
brilliant.org has a page on it
Didn’t you mop
no 💀
I dont understand when is a fraction
The fractions are just certain numbers between 0 and 1.
Those particular numbers have the nice property that the other trigonometric functions of the same angle will also be nice tidy rational numbers (which you can compute).
That way you'll have everything you need for plugging into the angle addition formulas.
Yall what resources should I use to study this syllabus. The document recommends Art of Problem Solving, Volume 1, 7th ed and Problem-Solving Strategies by Arthur Engel. Any suggestions?
arthur engel was my first book of maths
i highly recommend it
great book
yea its more a general book to start out then u can maybe look at books on what u wanna learn
for example pham kim hung has great book on algebraic inequalities
titu andrescu has great book on combinatorics
and justin steevens for introductory number theory etc etc
What competition is this syllabus for?
Harvard undergraduate science olympiad India
did anyone do usamts this round? it ended yesterday
I did
and @odd talon
yip not until later tonight
or tomorrow
yes, this round was my first!
only had time for 1 problem sadly
cause i learned about it a few days ago
me too
a + b = 10
ab = -11d
c+d = 10a
cd = -11b
Integrate (a+b+c+d) dx when a,b,c,d ≠ 0 and are not equal also.
[No ai Allowed, just try]
<@&268886789983436800> spam of the same thing across multiple channels
Replied to 'em in another channel, thanks for flagging!
hi!
I'm new to competitive math and i want to prepare for an entrance exam but I'm having a lot of trouble writing proofs... basically i'm am idiot pls help T-T
anyone done the UKMT SMC ?
yes
how wasit
it was okyay
In the future, you should give all the context when asking your question (so in this case, that would involve actually showing the solution where it says "WLOG").
Anyway, I looked it up, so don't worry about it this time. The use of "without loss of generality" is abusive - they're moreso abusing uniqueness (using the fact that there must be a unique answer as per the question format, so they're picking a simpler case to work with). This is supported by the solution saying later on that "this time-saving trick works only because ... a^2 - b^2 + c^2 will always be a constant" - unless you proved that a^2 - b^2 + c^2 must be constant beforehand, you cannot say a = 1 without loss of generality.
Wait so they just pull out a^2-b^2+c^2 = constant from thin air in the sol because idk, it's being asked?
yes
That sounds hilarious 
So it’s not a “correct” solution
And basically using wlog in algebra almost never works right
I only use it in geometry problems
Where sides aren’t given
There's nothing wrong with saying "without loss of generality" when it's actually clear that no generality is lost.
The problem is more that there doesn't seem to be any reason (other than metagaming) to expect that picking a value for a won't lose generality.
It's fairly bad form to pose a problem that gets so much easier by metagaming it (or, conversely, so much harder if you're purist and refuse to look at the answer options).
What’s meta gaming?
In this context, arguments that attempt to derive information from the fact that the question was asked at all.
It's not really a crisp technical term.
However, when we're done being disappointed with the problem setter, it's actually an interesting problem. The two linear equations we're given pick out a straight line in (a,b,c)-space, and it's really extraordinary that the quadratic expression a²-b²+c² would be constant along a line -- that's not something one would expect in the general case.
The solutions to a²-b²+c³ = D when D is a positive constant is a one-sheeted hyperbolid, one of the classical example of ruled surfaces.
I understand the line part that a,b,c satisfy are on a line but how one prove they're solutions of hyperbolid
That's where the problem is less than satisfying.
Are we doing algebra?
Well, I mean, ignoring the line, whenever you pick a D>0 and look at the equation x²-y²+z²=D, that gives you a one-sheeted hyperboloid.
But for proving that the line in the problem lines in one of those hyperboloids ... the algebra-bashing way would be to find a parametric equation for the line and plug that into a²-b²+c², then simplify and see that it becomes a constant after the dust settles. That's sounds rather cumbersome.
If you already know you're going to find a constant, it would suffice to find three distinct (but otherwise arbitrary) points on the line, evaluate a²-b²+c² at each of them and then see that those three values are equal. Then note that the only way a quadratic expression can have the same value at three different points on a line is if it is actually constant along the line.
Oh yeah, interesting but in fact we can do this w/o even touching WLOG, doesn't it just give the constant right away after doing so
math is weird
btw i think there's an embargo on SMC rn so don't share too many details
LY it's been such a while
how are you?
btw when the embargo's over u'll probs find more discussion of SMC in the UK section of mods
i'm good! wbu?
wait this isn't hlounge
lol i lurk here everyday i just don't msg every day
Bruh is that you who was once making this computer inside a simulation using rust
Year or two ago
Making circuits
well @high goblet are you born on 27 ?
no?
no
nvm
shameless self-promotion time! https://engage.usc.edu/scmathcompetition/scmc-fall-2025/
mee
Did u get cooked or did u ace it
I’m a 15yr old doinf it
I only managed to do 21 of the questions
i use alcumus for problems specific to a certain topic and mathdash to test my knowledge
tbh, i use mathdash more often and just skim through alcumus problems
did all 25 but internet crashed at the last minute
so i dont know whether all my answers saved
😭😭😭😭😭
me2
Sweat
no 😭😭
all my orher school friend only did like 15+
it was really hard ngl
Is there any list of like
recommended exercises for aops books
why do they have. So much.
Honestly js grind it out
It’s long but worth it
If u master everything in it ur set for a lot of comps
Guys
How was the ukmt smc 2025
I just marked my paper
Do you think the grade boundaries for bmo will drop
Like prob 104???
does anyone know how to answer this imocsea question
if you draw out the rest of the circles, it's easier to find the area of ABE as half of the intersection of two circles that go through each other's centers
then you can just take the area of each quarter circle and add them, subtracting ABE, and then subtract all that from the square to get DEC
Area(DEC) = Area(Square)-Area(DAE)
-Area(CBE)-Area(AEB)
Area(DEC) = 2×2 = 4
Area(DAE) = Area(CBE) = (30°/360°)×pi×2²
= (1/12)×pi×4 = pi/3
Area(AEB) = ½×2×sqrt(3) = sqrt(3)
Area(DEC) = 4-(2pi/3)-sqrt(3)
5th grade math in china (jk)
eh i dont think this would be unreasonable for a strong 5th grader
THANK YOU
China math built different lol
hlo
https://www.scribd.com/document/825240426/2022-Questions-AIMO-Open-With-English
this is 5th grade in Hong Kong
they already have these
the whole paper is lower secondary difficulty: these concepts are usually taught in 8th or 9th grade
but if kids go to competition maths tutoring, they learn them earlier
I can see my friend tripping over these problem
That's scary
I'm not saying these are hard, but most people don't know how to do these in 5th grade
just like most people can't do AMC8 problems in 5th grade
Wow, that's horrible notation in (11).
crazy
Are there books based on such problems?
I know
@ornate blade do you know where I can find such problem sets for competition math?
Sub tenth grade level
there's also AMC10
what are AMC
also if you register an account on AoPS you can get Alcumus problems
Now I take a closer look, do 5th graders here know a^2-b^2=(a-b)(a+b)
scary in anyway
and a^2 +(-) 2ab + b^2
My 5th grade cousin asked about telescope sum once but it's in term of product not different of square like this bruh
i wish i learned math in a way chinese kids learn it because its looks so easy for them while im struggling here lol
most Chinese kids also find it hard, especially in secondary
just cause the teacher is teaching at a million miles per hour doesn't mean the students are following
Nahh you dont want to study for 12hours/day 💀
also like contest maths is different from regular school maths
regular school maths is definitely not this advanced
i already do that anyways 😔😔
7:30am to 7:30pm
ehhh I'm pretty sure they start thier day at 7am
But that's still kinda crazy
we got to school at 7:30am but class wouldn't start until 8
cause if the school buses left any later, we'd spend way more time in traffic
Tbh i dont even think im gonna pass imocsea 😭😭 goodbye japan trip
same for me at hs, bus gets there at 7:40 then class at 8
oof rip
i mean if it didn't save in the end and you think doing bmo1 would be beneficial you could always pay for a discretionary
i did hear that this year's smc was found to be harder, but i've also heard otherwise
In the future, please show what you’ve done so far when asking for help - it gives us more context of where to help you (and saves our time from explaining things unnecessarily). \ \
By definition, we have
$$I=(A^{-1}+B^{-1})(A+B).$$
Now, consider expanding this.
Civil Service Pigeon
Further hint: ||Multiply this by A.|| On the same thread, ||multiply by B as well.||
no i already know the solution
i just was wondering how someone else would solve it
Well then, ideally you should mention how you've solved it, and if other people then have a different idea to yours (or otherwise aren't happy with how you've done it), they can then say that to you 
oh okay
FWIW that seems to gets me nowhere.
Well, it does lead to a 2×2 counterexample with complex entries (||A=e^(2ipi/3)I, B=e^(4ipi/3)I||) , so the real case cannot just be an algebraic sleight-of-hand with determinant properties ...
$$I=2I+A^{-1}B+B^{-1}A \implies A^{-1}B+B^{-1}A+I=0$$
Multiplying this by $A$ and $B$
$$\begin{cases} B+AB^{-1}A+A=0 \ BA^{-1}B+A+B=0 \end{cases}$$
And so
$$AB^{-1} A=BA^{-1} B$$
Taking the determinant of both sides yields
$$|A|^3=|B|^3 \implies |A|=|B|.$$
Civil Service Pigeon
How did I miss that?
help
First, "right triangle where the square of the length of the hypotenuse is 4 times the area of the triangle" lets you conclude something very specific about the angles/lengths in the triangle.
bro can someoen helptho!
Fairly sure I'm not your brother, but I did post a hint.
is studying 1-2 hours a day enough to prepare me for my mathcounts chapter competition (in late feb)
if i qualify for state, i would prob start studying 3-4 hours
cool
let a,b be the 2 legs. It is given that a^2 + b^2 = 2ab --> a^2-2ab+b^2=0
what can you conclude about a and b
Let length of the 2 legs be a and b and length of hypotenuse be c
using Pythagoras we get:
a² + b² = c²
c² = a² + b²
Area = ½ab
therefore:
c² = 4 * ½ab
c² = 2ab
a² + b² = 2ab
a² + b² - 2ab = 0
(a - b)² = 0
a - b = 0
a = b
thus the right triangle is an isosceles right triangle
since it's a right triangle the circumcenter lies on the midpoint of the hypotenuse (Circle Theorem)
and one of it's angle bisector is also the height which connects the point of the righr angle to the circumcenter
thus it also bisects the hypotenuse since it's isosceles
hence option (A)
hey can someone help me out here, i keep getting 9216 on this after a few tries but my answer sheet says 9210
does anypne know what happened to aops? i literally can't find any webpages that are actually helpful
i wonder if it's my disable google ai extension?
or did its seo get fucked majorly
everything's still on their website
Ehhhh it's because: when one of the boxes is empty
Take 1 way in case one for example:
B1 B2 B3
Now let's say B1 and B2 are supposed to have even numbered balls but B1 is empty
And take one way in case 2 :
B1 B2 B3
Let's say B1 and B3 are supposed to have odd numbered balls but B1 is empty
Even though the assumption for 2 case are different
It's basically the same, as B1 have no ball , B2 has all the even-numbered ball and B3 has all the odd nunbered balls
There are, I guess,6 cases like this
I guess they mean that a box with zero isnt odd or even
Thank u mane
Wait it says a box can be empty
But the weird thing is that if any box s empty then the other 2 boxes satisfy the conditions
Since its 11 odd 10 even
no
oh wait
yeah lol
ehh not sure wym here
вфьт
you are also counting cases where 1 box is empty
so you need to subract them then re-add the number of cases where 1 box is empty
in each of case 1 and case 2 there are 6 cases where there is 1 empty box
so total 6×2 = 12 cases
9216 - 12 = 9204
and there are an overall total of 6 cases where there's 1 empty box
so 9204 + 6 = 9210
thus the reason you get more than you should it's cuz you counted the cases where there's 1 empty box twice since they are the same case in case 1 and case 2
Take cases where you place all odd numbered balls only(11 balls) , even balls (10 balls) only, 1 box odd and 2 even and finally 2 even 1 odd
Use formula (n+r-1)^ C (r-1)
n is the number of Balls to be distributed
And r is 3 (to be distributed among)
And -1 is for empty boxes allowed
Hope this hint helps you
nice
i have been attempting olympiads for past 3 years
Hey so I am taking amc 10 and 12 and I was wondering if any of yall know a comprehensive study guide over the topics covered since I'm having some difficulty finding good pages on the web
make one yourself
how?
23C2
,w binom(23,2)
Ehhh the answer for that is 9210 if that's what you meant
And
Dude
Let others help if they want
Their solutions may be easier than yours
I js mean let others answer if they want too!
You are not supposed to give out the sol here
i know
Ehhh, yeah that might make this channel feel more alive ig
but things ain't always according to Book
now you got it correct
hi guys
Calculate |Z|^2
Its extremely hard compared to olympiad questions but its not a reason to not try
$\begin{cases} n, & n \text{ odd} \ 2n, & n \equiv 0 \pmod{4} \ 0, & n \equiv 2 \pmod{4} \end{cases}$?
Civil Service Pigeon
$$|Z|^2=\sum^{n-1}{k=0} \sum^{n-1}{j=0} \omega^{k^2-j^2}=\sum^{n-1}{k=0} \sum^{n-1}{j=0} \omega^{(k-j)(k+j)}$$
Now let $m=k-j \pmod{n}$. So,
$$|Z|^2=\sum^{n-1}{m=0} \omega^{m^2} \sum^{n-1}{j=0} \omega^{2mj}$$
and the rest should be trivial if I'm not an idiot
Civil Service Pigeon
Ggs
I have this pretty interesting problem that I haven't been able to fully solve
Using 12 iron bars to create the frame of a rectangular box with dimensions 20, 30, and 60. When placed outdoors, the edges of the box cast shadows on a flat surface. Assume that all the light rays are parallel. Determine the minimum and maximum values for the total length of the shadows of the edges
This's the whole problem, if you're curious. It doesn't state how the box is placed
You can ask Carbo 
well, we discussed it ourselves already
he doesnt know
i mean he showed me the question so
damn, must be tuff
||Let AE intersect BC at G. Easy to see that GF^2 = GD^2 = GB.GC. Let H lie on line BC so that G is the midpoint of HD. We get C, B, D, H as a harmonic set of points and F lies on (HD) -> F lies on an Apollonius circle||
hm
that's fucking smart
Is answer zero
hard compared to olympiads 😭
In the future, please show what you’ve done so far when asking for help - it gives us more context of where to help you (and saves our time from explaining things unnecessarily). \ \
I'd do this by counting the complement. There are three cases to consider:
\begin{itemize}
\item All $6$ digits are the same.
\item One digit appears $5$ times and a different digit appears once
\item All the digits are distinct
\end{itemize}
Civil Service Pigeon
what i did was consider total cases as 6^6
then subtract cases where nothing gets repeated thats 6!=720(so i get cases where alteast one gets repeated)
then subtract 2 more cases
not repeating 5 times that is 6x6x5
not repeating 6 times that is 6
so i got 46656-720-186
that is 45750
yeah but its hard to search for resources
when i search amc12 i literally cant find aops unless i specifically google forit
this is MODSMO?
anyone got some grade 11 question for competitions and could help out with them?
what competition
math
wdym which
like my city's
grade 11-12
well technically 9-12
Well then I don't have any of those I don't know what your city is
yeah no i get it but im just looking for some coaching
since every time its different problems
Ive found some that could be there
do i send it here or message you?
It would be better for one who knows or even have participated in that comp coaching
no, I don't think I can. I'm senior highschool
$What fraction is to the n^{th} power?$
Average_X^2
yes
is anyone here doing the carnegie mellon winter math comp?
IS ANYONE DOING JEE MAINS OR JEE ADVANCED OR CMI OR ISI
YES
Not me but JEE takers here are numerous
Well not that many but we do have
I also know some
WELL IS THERE WHO CAN HELP ME OUT
A PROBLEM
just send it here lol
OK
CAN YOU MENTION SOME
sorry mate I can't ping them for no reason
OKAY
yuri...
W yuri!
competition math channel is so weird lol
wdym
Why is it so?
cuz i cant see any discussion which is remotely related competiton maths (talking about IMO/putnam etc)
i see homework problems mostly but nvm
It's fine, atleast the channels are active a bit
You can't expect people who are grinding for comp to be active
They're in their 24 hours study session
That if you would say 2×4 and 2+4 are the same

what tf do u even mean by that lol
also i have done fair bit of math olympiads those exams doesnt mean u have no life lol
I just meant that they spent so much time grinding
i literally participated in maths olympiads
u dont "grind" all day
also anyways this server has many working mathematicians who have fairly more work to do in that sense then but i think just quality of this channel is poor thats it

Yeah could be
there r advanced channels below
Ngl I had like 6 hours back when I was studying for comp...
6 hours hw
For a day
After that I say no more for competition 
just send it here lol
false.
this is not r/mathmemes keep your unfunny completely inaccurate generalizations of olympiads out of this channel
i think it's also bcus everyone who's seriously studying for maths olys will be discussing in MODS
(linked in channel description)
so mostly the ppl here will be those new
any good resources for combinatorics for math olympiads for begginers like for coloring invars monovars and stuff with problems
who else eagerly waiting for usamts round 2
Any suggestions for preparing CSMC?
Go to Aops
how hard is amc10 and amc12 compared to like calculus 1
Way harder
No not really
does anyone have suggestions for mathcounts? its my last year and i need to lock in on chapter sprint rounds i average 21/30 in 40 mins but thats not good enough for my schools team. i practice with rounds from 2019 and everything but i always struggle around the same point
i think im supposed to ask that here
Hey there, turts, I did mathcounts as well with a lot of good people, I think I can help you out! So what I think would be best to do is go to aops, and find the art of problem solving books for competition math, if you haven't already. Also doing mock tests is pretty helpful. I hope you have great time at mathcoutns and do really well!
For the books try AMC 8 and MATHCOUNTS Level
There may be harder level problems but getting those right just means your even more prepared
got it, thank you very much!
No problem
Hi I’m in 6th grade can u help with this math counts question The second round of the Major League Baseball play-offs is “best out of 5,” meaning that two teams will
play each other until one team wins three games. How many different ways could this play-off match-up
This is an AOPS question for my homework
the best way to solve this is most likely just to casework on the # of games played
They either play 3, 4, or 5 games
btw, if youre under 13 you cant be on discord
That if you would say 2×4 and 2+4 are the same
Nahh
Wrong
It's 8 and 6
I feel 13 is the minimum age one could expect you to understand that companies mine your personal information online for profit
it's already a nebulous concept for a lot of adults
✨Why ✨do ✨you✨ care?✨
Is anyone here preparing for IMC( international mathematics competition) undergraduate or you know someone ?
I see
i care for other peoples safety
just making sure hes aware dam
Safety? Oh yeah, if statements like that are just keeping people safe then I'm freaking jezus
how does comp math even work
What do you mean? Are you asking how competitions happen practically?
yeah
It varies from competition to competition, but a typical format will work more or less like a written exam, since competitions tend to be organized by or in collaboration with school systems. The problem sets are designed to be so challenging that even very good participants will not have time to answer everything perfectly; this makes it possible to speak about who did best.
hi i have a competition this afternoon, its 5 am rn lol
do u guys have any study guides on the theorems?
especially binomial theorem and stewarts theorem because i genuinely dont know
oh also chinese remainder theorem i need to study theorems
If you haven't slept already, doing that will help you more than any amount of last-minute studying will.
A man and his dad put a bomb in the sink
i already slept
and im cooked for my exam thats why i woke up early
man + dad = bmb + cnc?
is that stewarts?
Yeah
Does you Binomial Expansion part include Combinations and Binomial Probability?
I don't know the context of your competition, but studying Pascal's triangle and the general expansion form of the Binomial is a good way to do it
Wrong
pascal's triangle is like day 1 example to introduce binomial coeffs 
It goes deeper than that tbh
You can visualize every theorem with pascal’s triangle
ok then tell me how is fermat's last visualized with pascal's triangle
this is 334 right?
hey im preparing for a math competetion next month its called georhr mhor and how would i study for a competetion its largely focused on geometric knowledge and combinatorics and some trigonemetry but mostly angles but i could use some help
i think you should make a tree diagram
im trying to do the amc 12
ooh how is it
heard the competition is soon
Its so asian
Got a problem at some idk what paper
Let F be a field and let f(x) = F[x] be
an irreducible polynomial of degree n.
Consider the field extension
K = F[x]/(f(x)).
Let a Є K be the image of x under the
canonical projection. Prove that:
- K≈ F(a), the field generated by a
over F. - Every element of K can be uniquely
expressed as a linear combination
ao + a₁α + . . . + an-10-1, where
ai Є F. - If f(x) is separable, then K is a
separable extension of F.
is it bad that i remember this exact problem
theres actually a really nice way to do this
you can let the LHS be a second degree polynomial
cause x_1, x_2, etc are just coefficients of some terms of it
then you can set whatever
and its like f(1)=1, f(2)=12, f(3)=123 and you can find f, then answer is f(4)
Bubo. Orz!!!
orz
??
anybody got advice on youre first math competetion
prepare months in advance
dont learn new topics the day before
just review if possible
Ikr why is everyone Asian like specifically Chinese
Don’t mean to be racist
what do i do if i got 2 days
just relax ngl i went to a kangaroo math comp a while back and i fumbled so bad bro because i was so stressed i couldnt think straight
Just do a shit ton of practice problems and learn theory on the way tbh
You could use resources like amctrivial, aops, etc for problem sets to do
i wrote the question in the top left where it says log2(x^2) + 2logx(8) = 392 / [log2(x^3) + 20logx(32)] given x > 0, can someone verify if i got my a-substitution calculations right
,w log_2 (x^2) + 2 log_x 8 = 392/(log_2 (x^3) + 20 log_x (32))
oh ok thanks really needed that
pray lol
its the nerves that get you during your first competition
Hello, Dhruv!
We have situations:
WWW
LWWW
WLWW
WWLW
LLWWW
LWLWW
LWWLW
WLLWW
WLWLW
Then this could be for either team's perspective. Therefore, 18?
I am not sure, however.
Hello, everyone!
What are some book recommendations for AMC10? I aim to make USAJMO this year but have my 8th grade (next year), my 9th grade, and my 10th grade years.
I use all books on the AOPS Book Store, handouts, AMC books, formula books, and other resources found on https://mathematics.gg/books.
I'm writing this year's Putnam. Not exactly the IMC, but I would be open to practicing those kinds of problems too
Is there anyone here that went to community college and participated in AMATYC?
Everything in here lowk making me tweak
Do they cover this stuff in a levels
I thought this was meant to be pre uni 😭😭
fr tho! i'm here doing good (for my year/grade), then see this and start thinking i just have a dumb class 😭
I even tried learning some of the content myself
To get ahead
And come here just to be humbled
What's the matter dude?
um so im in 10th rn, im in imo rn, what other stuff shoulld i enroll for??
like maths related
or anything else
i signed up for imo il be writing it in like a couple weeks
or anything if im being honest, not specifically math
my extracurriculars are kinda ded
chat
anyone here participated or will participate in International Youth Math Challenge?
I did it last year
any advices or what resources did u use
you could do more olympiads, like smaller ones
depends on where you live and what olympiads are available, but there should be at least a few
Should I study for the Putnam exam while in high school?
Does it help my academic journey in college?
I really need an advice on this, I find the material in the exam interesting. Also I'm doing well in my senior year and I want to try smth out. Is putnam worth trying?
ya valid
here qualifying for the national olympiad tea,'s a big deal
i cant find anywhere to continue coursework tho
like the required coursework for the prep
like combinatorics which is extremely out of portion to the stuff we learn in school
I qualified for the final round, but I didn’t pay for it because I thought it wasn’t worth it. I heard that the final round is very fast paced, maybe practice doing early AMC8/10/12 questions within 1 minute?
I don’t know the difficulty of the problems in the final round, so the suggestion is quite off
umm why not worth it ? so the whole competition is not necessary?
like is it a waste of time
In my opinion, yes. It’s not necessary because I don’t think it is that prestigious. You can do it just for fun and get a certificate, I don’t think 10 quid for a certificate is a bad trade at all. I didn’t do it because I knew I’d get stressed about doing well on the final round and divert my attention away from things that I actually wanted to do
Ok thank you so much
from my experience almost no one actually studies seriously for Putnam
the MIT kids who dominate every time are coasting off their very strong HS Olympiad preparation
and you’ll be busy with more important things during your undergrad anyway
IMO? What country
Hello, pls help.
how to do it
Poly(^///^)
||you can brute force this, 7^2 aren't that many combinations||
Guys how many hours do u study for math competition per day/week?
I know it depends on the type of competition and many other factors, but in general?
Usually 1h/day
Sometimes 3h/day
From what I remember
Which competition were u preparing for?
India
i assume the IMO he's referring to is not the international math olympiad cuz u can't really sign up for itt
U qualified INMO
And got selected in team?or is it some private olympiad
It must be some private olympiad
Because to get selected in imo team u need to clear many stages and only 6 students from a country are selected
yes
no i mean the school titles it as imo
i mean ur really just writing lke prep for the exam
qualifiers essentially
yup
ik
i rly dk y its titled as such
but that the name given to the exam
and ill write it soon
for th imo team i undertsand u have to write rmo
and a bunch other stuff
im rly not good enoughf or that stuff
soo if any of u have written the rmo in india
i was wondering if u guys had any tips for prep
balancing it with other prep like JEE stuff and what not
This year i gave ioqm
Wont appear for rmo because im preparing for inpho and jee
My score was 48
any suggestions
ill prolly write it after i finish boards
ic
what abt the syallbus
im too lazy to search it
send pwease
i genuinely have no idea of any kind of math outside 10th syllabus, but i've always wanted to learn
seems rly fun
is it ?
ru ICSE or CBSE btw ?
In icse only history and geography is dangerous
oh i got fried inhista nd geo
*in hist
mid term
i rly dont wanna talk abt my marks rn
🙁
R u in any foundation program?like i was also styding 11th with 10th
Next year give the olynpiad of the subject in which u have interest
Like maths ioqm
Or physics
*Dont
If ur syllabus is completed try to start the syllabus of class 11th
is the answer to this one 0?
no
interesting
its a fraction
ah, I made a mistake when considering the polynomial ||(sqrt(x^2 - 1)^20 + 1)^2 - (7 sqrt(x^2 - 1)^3)^2 = 0||, so yeah, I see how it's ||187/53|| now
absolutely correct
they actually teach this method of root transformations in A level further maths
as for the first question, I have zero idea
correct approach
this was in IOQM
really?
I'm actually surprised you understood my method based only on that
when i see a question thats interesting
i try to see all the approaches to solve it
so yeah
this is a monster tho
oh wait
cyclic expressions maybe
spoiler link for the 1st question: ||https://math.stackexchange.com/questions/3825746/find-the-value-of-the-sum-600-sum-a-1-infty-sum-b-1-infty-sum-c||
I solved it
where did u get this from????
IOQM
anyone else qualify for BMO1?
anyone else is argentinian and qualify for OMA national olimpics?
This one Js pfd the denominator
1/2(1/r+i + 1/r-i)
And then use a polynomial root transfer to create polynomial with roots r+i
And another poly with roots r-I
And then viettas
No
ioqm is the qualifier
and no that problem is not from IOQM
It's from a random jee channel called "JEE SIMPLIFIED SUBJECT"
like, IOQM is just a qualifier instance
ioqm is a qualifier for the regionals
from where?
and if you qualify regionals you go to nationals
which nationals?
like, from which country
oh India


I gave no solution