#competition-math
1 messages · Page 17 of 1
It’s so over 😭
I “proved” it’s not possible for anything other than 3
Has anyone heard of the ISMTF Olympiad?
did you do sine rule way
what are you thinking for silver and gold medal bounadries 👀
oh well
nah i just synthetically did it
let AM meet circle BPC at point Q then finish
probably like 45+ or 50+?
gold will be leaderboard, silver will be just below leaderboard
how did u do?
I’m not sure but here’s my solution: @hidden oracle
Parameterize the position of each point by a range of [0,1[ with 0 being the beginning and 1 being the full rotation. We fix the first point A at 0. This way, the total volume is just 1x1x1 = 1, so we don’t need to worry about this factor and the winning volume gives us the winning probability. Choose B, C, D such that 0 < B < C < D < 1 or 0 < D < C < B < 1 for a convex quadrilateral. The next part is where I am uncertain. I believe that if I interpreted correctly, these both give the same graph of a right tetrahedron like in the picture, with volume 1/6.
Ok so looks like I indeed messed up the graph so the answer is indeed 2 x 1/6 = 1/3
I was wondering, there shouldn’t be overlap between the graphs but the first one is like x+y+z < 1 that’s why it’s symmetric (wrong)
Hi everyone, other than AoPS by category, where can I train specific AMC 12/AIME topics individually?
i think i can get silver then
i got 2-6 (solution seems a bit weird for 6 just did some repeated php magic we will see what i get when it gets marked but hopefully 10- at least)
for 1 i did huge wlog fail, provided construction for n = 3 and proved that you can have it for n >= 4 if you have an increasing sequence of length at least 3 within your circle
im guessing like 2-3 marks max for that lol
oh damn nice
do you lose marks if you state something untrue after
what was ur soln to 6?
we mark by the principle "if a subset of the soln is worth 10, then the soln is still worth 10" lol
because for this after i tried to prove you could only have increasing sequences anyway (?? not sure what i was thinking here)
uh like map each cube to a co-ord 3d grid and do php with like 3d pythagoras
huh interesting
there's a cute way of doing it with pigeonholes directly
split ur cube into 8 2x2x2 cubes
then you can split each of ur 2x2x2 cubes into 2 bits by a 'chessboard' pattern
and then that basically finishes the problem
that's quite nice
this was the soln george found when he was very drunk lol
i did 5 with orders
how?
is this george z
yeah, IMO 2022
well order has to divide 6 so order has to be 1, 2, 3, 6 then prove it doesnt work for 1 or 6 and then you can show for the order equalling 2 it divides one of the expression and for order equalling 3 it divides the other expression and that the only possible orders are 2 and 3
let me know if you spot it or find any funny solutions
where did people get stuck with 3 is it just a you either spot it or you dont question
i'd imagine so
nah
you misinterpreted it
how did you show ord_p(n)=6 is impossible?
Ok yeah it was much more involved apparently
https://math.hawaii.edu/home/pdf/putnam/2006.pdf
That's Putnam A6
Oh damn never knew that
Any idea how to do the first problem
Yeah its 135
anybody know what this function is?
The question says: 17) What is the expanded function term?
math hurts my brain
Pure Mathematics
Is it a Green function 🤓🤓
Well…actually🤓👆
does anyone know a synthetic proof of the existence of isogonal conjugates?
What do people think bmo2 qualification mark will be
30ish potentially? what r ur thoughts?
i heard ppl found it to be a hard year
maybe 33-35 for Y13?
same

i got a ping here
idk
huh
Hi

Is there a better way than PIE/casework?
How many distinct five-letter permutations are possible using five of the letters in COMMITTEE?
probably not
it's pretty fast in this case
well i'm not sure i understand the task
I think casework is slightly simpler
you don't need casework or pie
it has MM or TT or EE and never two pairs
like if a word is MMEEC
that's using 3 letters
but they want 4
oh it was a typo
Yeah I edited it from a mathcounts question and forgot to change the last part
It was like the same question but 4 letters from MATHCOUNTS
i don't see how pie would work, it's two three cases yeah
one pair or two
or none
Oh wait it's disjoint I just realized so PIE is not needed
pie would be like, 3(words with MM) − 3(words with MM and TT)
Ok
but words with MM are hard to count, basically back to square one
hmmm
i started to cancel things out from the top, but it turns out that i should be starting from the bottom to cancel things out or else the result would be entirely different?
hmmm?
i think the intended solutioon is to separate 1-7 and 8-14
and then you just continue wiht it
im not sure what you tried to do
Yeah but they started cancelling numbers from 8 to 14
But what i did was going from 14 to 8
So i was wondering how i would figure out to start from 8
But the result comes out differently
i think you did it wrong
Because cancelling from 14 it’s 1x6x5x …
Rlly?
yeah i dont think you can cancel it like that
it doesnt work because if yoou start from 14
lets say 14 pairs with 7, and with 1-6 and 8-13
you cant just set it up with any combination
since when going from 6 x 5 x 4 x 3 x 2 x 1 means that any pairs are possible
but when you start from 8 you wont overcount
4 x 3 x 3 x 2 x 2
Ohh
Thank you
Ah
what's BMO?
💀 no one does that
It's the other way around because imo qual for US is way harder
@pallid dragon I forgot, you can use generating functions
Since we have 3 letters appearing 1 time and 2 letters appearing 2 times, we simply find the coefficient of $x^5$ in $5![(1+x)(1+x+\frac{x^2}{2!})]^3$
victor
Hopefully no mistake was made
What about China TST
Jk
Check using casework over number of pairs:
base factor: 5!
Case 0: 6C5 = 6
Case 1: 6C4.3C1/2! = 30/2 = 15 ??
Case 2: 6C3.3C2/(2!)^2 = 15 ??
Wait what
Did I mess something up
Oops
Check using casework over number of pairs:
base factor: 5!
Case 0: 6C5 = 6
Case 1: choose 1 pair of 2 and 5-1x2= 3 remaining from 6 - 1 = 5
3C1.5C3/2! = 15
Case 2: 3C2.4C1/(2!)^2 = 3
Hence 120(6+15+3) = 120(24) = 2880
hmm never thought abt that, are US and China imo teams pretty even?
Bruh of course it was a silly, I wrote 1 instead of 2
Ok both work very nicely then
No
The china tst is much harder than the imo
I’d say getting on chinas imo team is more of an accomplishment than getting gold (you’re getting it anyway)
Like silver medalists and bronze medalists will never get into china’s imo team
so is usa tst and usamo right
From their past scores idt it's by a lot right
☠️
No
I’m not a mopper so my opinion doesn’t matter tho
usamo is not harder
wtf are you yapping about
from what ive heard usamo p1>imo1 but imo3>usamo3
debatable
Uh
u sure this is harder than imo p1
@ornate coyote you should be able to solve this
dont we just use a short induction
ye
if you draw 4 different segments randomly
what is the probability that you make a triangle that has all 3 points on the circle
so basically you can find out how many sets of 3 points you can pick
to be the vertices of your triangle
and then place the last segment
ok depends on the year
but usamo is not like a lot easier than imo
This is not true at all
my fault gang
i can always kill imo1/4 but i sometimes cant do usamo1/4
so thats what i thought 💀
Well there are differences in "problem flavor" between contests
Maybe IMO just suits you better
yeah guess ill have to make it to imo this yr 😔
Trying out small values, there is a very interesting pattern:
5
75
375
9375
59375
359375
So it seems like we can just stick an odd digit in front. Let’s test this hypothesis:
By induction:
The base cases n=1,2,3,4,5,6 hold.
Now suppose we can append a digit in front. For length n and numbers x_n = 5^n m_n, we set
x_n+1 = d10^n + x_n = d10^n + 5^n m_n
where d is an odd digit.
We need x_n+1 == 0 mod 5^(n+1). Set
d10^n + 5^n m_n == 0 mod 5^(n+1). Equivalently, dividing by 5^n, we simplify to
d2^n + m_n == 0 mod 5
d == -m_n 3^n mod 5
We need to show that this is possible for odd digit d. Notice that for any residue mod 5, within the digits from 0 to 9, we have exactly 10/5 = 2 digits with that residue, alternating between odd and even. This means that there is exactly 1 odd digit that fits each residue mod 5. Hence we pick d to satisfy the and we have constructed x_n+1, so by induction this holds for all positive integer n.
I wonder, is this solution not unique? Can we construct different solutions by not sticking a digit in front? Or can we prove it is unique?
brit math olym
Pure Mathematics
Hey, is there anyone competing in PMO?
dont think the 26 matters here for parity
just do $\sum_{d|n, d\neq n} d$
buboblakistoni
$s_{26}(n)$ has the same parity as this
buboblakistoni

Find all integers $(n, m)$ such that $(10n + 4)^m + 4$ is a perfect square.
al
Equating to k^2 and all the usual tricks don't seem to help with this, can anyone a) verify that this has any solutions at all and b) give me some insight into solving the problem?
Taking mod 5, doesn't have any solutions, as I thought. Kind of a troll question
um hi
Yes this is just the complement of number of perfect squares from 2 to 100 if I am not mistaken
Powers preserve parity, so s_26(n) == s_1(n) mod 2. If n is prime factored as n = 2^e_0 p1^e1 p2^e2… then the parity of s_1(n) depends on the number of odd factors.
Each even factor added doesn’t change parity, so we can safely ignore them. For odd factors, the sum will be odd if and only if the number of odd factors is odd.
Hence, by cases:
n odd: we subtract 1 to exclude n from its proper odd divisors so
(e1+1)(e2+1)… - 1 is odd iff (e1+1)(e2+1)… is even (if and only if at least one odd prime factor has odd power)
n even: n doesn’t affect parity of s_1(n), so
(e1+1)(e2+1)… must be odd (iff all exponents are even, meaning n is a power of 2 times a perfect square)
does mobius transformation work here LOL
s_1 isn't the number of proper divisors, it's the sum of divisors
anyone doing ritangle here?
Is there a questions pdf
When’s round 1 and 2
And what’s the selection like
Wait true I got confused while writing here, I accidentally overwrote my message while editing another one
Powers preserve parity, so s_26(n) == s_1(n) mod 2. If n is prime factored as n = 2^e_0 p1^e1 p2^e2… then the parity of s_1(n) depends on the number of odd factors.
Each even factor added doesn’t change parity, so we can safely ignore them. For odd factors, the sum will be odd if and only if the number of odd factors is odd.
By cases:
n odd: we subtract 1 to exclude n from its proper odd divisors so
(e1+1)(e2+1)… - 1 is odd iff (e1+1)(e2+1)… is even (if and only if at least one odd prime factor has odd power)
n even: n doesn’t affect parity of s_1(n), so
(e1+1)(e2+1)… must be odd (iff all exponents are even, meaning n is a power of 2 times an odd perfect square)
Complement should make things easier to count for case n odd, while n even you can probably use direct enumeration.
Total odd integers from 2 to 100: 3 to 99 so 49.
Bad cases: All odd primes have even power, hence it is an odd perfect square.
9,25,49,81
Good: 49 - 4 = 45
Now for n even:
9: 18,36,72
25: 50,100
49: 98
81: none
Hence 6 good cases.
Total: 51
Guys if you could help for this problem below, I can pay for it: https://discord.com/channels/268882317391429632/1310148924836806656
Google it
It’s pretty easy to qualify for the first
Second is much harder to qualify than first (at least for me)
$x+1=2$
Aestusy
You need solution?
I don't know man this seems like Liouville's Theorem i guess


yo yea im doing it
Where is this from?
Explanation: the first lattice point hit after (0,0) must clear the denominator of 5/8, so we multiply by 8 to get the point (8,5). Hence, the number of reflections is the number of grid squares travelled mod 2.
Vertically, we have 5 == 1 mod 2, so we have 1 vertical reflection which gives the top side.
Horizontally, we have 8 == 0 mod 2, so we have 0 horizontal reflection which gives the left side.
Hence it is the upper left corner.
(In the pictured I scaled each step of (1,5/8) to (5,8) so the intuition was easier with integers, but this is not necessary)
Which contest?
27th Philippine Math Olympiad (Qualifying stage)
math is hard
As long as one doesn't try to understand it
I found British math Olympiad
I would say definitely no need for so much bashing, just clear the denominator to ensure you land on a lattice point, then reflections applied twice give the identity so we can just consider the numbers mod 2
Wow, problem 8 is very beautiful
Thanks for sharing
It seems so complicated at first but with induction it gives a contrastingly elegant result
i dont have a decent foundation in NT or mod stuff, so it was the thing I thought of doing
but most of the trial and error part can be done mentally
so yeah, it can be thought of as clearing the denominator
Well you can just notice the pattern that it always goes LRLRLRLR UDUDU so only the parity matters
Balkan Maths Olympiad
me leavin the class after said Mary gave birth to 2,5 kids 
How can I solve it in the second way.
Stage 3 wbu
I tried number soup
they cooked this years stage 3
I got a solution but it doesn't fit the same digit present rule
Ohh fairs keep trying there is one
I finished number soup and triangles but can’t do genius 3
I feel like I've tried every possible one
na say ong 😭
Yea I'ma try genius 3 now
yo that’s actually insane
how did you practice
dam
do you need 100% for a 9
mines next year so just tryna get info on this shit
fucking he’ll
hell
dam
that’s actually sick dude well done
Jk, But fr good job
I haven't seen the paper, I tutored someone TMUA tho, not sure what they got
not even full marks smh
anyway gj tho!
u applying ox?
ic ic
which college?
ic
well gl with ur application process!
oxford still haven't sent out interview offers right?
oh fairs
how did the MAT go for u then?
fairs
stayed 2 hours after school and solved it
wow
you doing IB by any chance?
oh no i dont
just asking cause 45/45 is a perfect score in IB
think a kid got 59 in my old school, he did 2 extra HLs
is this the 3rd round?
Yh stage 3
you solved genius 3?
Yh as a team
oh shit did you do it by code?
ohh fairs so you guys solved everything already?
a code for the QRS
Wdym already it's been 5 days
That's like a whole week
Yes
We spent 4 till 12
4 hours?
No 8
St Gregory's
dam never heard of it
dawg 😭
It's like St Catherine
It's like connected to my secondary
How far are you
dayum how many people are in your team?
like into the competition?
Yh
6*
5 but like 3 of them are mostly offline
done everything except genius 3
There was 10 originally but they don't do anything
guess il at least get an honourable mentions or sum
genuinely can’t figure this shit out
Think some schools solved it way before
you get an honourable mention if you manage to do 2 of the puzzles
The group leader somehow found the max digits for each clue
we did as well
but can’t figure out from there
guess gotta do it by hand
this shit long tho
might as well give up
What were you doing
me and my partner doing it by code :p
that’s how we solved all of the puzzles so far so we thought it would work 😭
Huh
Even the letter stuff
yeah
I guess PQRS too
yup 😭
Technically you could have entered stage 3 without pqrs
oh yeah maybe but
It's literally in the name
Ngl for like the first 10 questions on stage 1 we thought it was only 1 try
dawg 😭
We were super careful lol
wait are you guys in year 12 or 13
12
dam
Can 13 participate?
Oh arl
applications already ended
Oh
uni applications
Only code I made
Took a few hours
oh fairs
Apparently we need working out
yeah
wdym you can’t find them
No physical copy
oh
thought you can just have a digital copy
are you guys sure your gonna be the winning team?
No
Still a possibility never know
dam alright
Btw is rectangle world wide
Yh we are done for
Oh
Can't lie I have no working out for modulus graph
Just used desmos
I mean that’s appropriate use of technology so it should be fine
did you guys already like pre learn further maths and stuff
Uh no
But I know some stuff
what did you guys do for like question 26 then
Already completed a chapter we are not ment to do
Wdym
the probability one
one of our mates had to use like a further maths topic to do it
We made a 1x1 square and did like integration or something like that
could you give any tips for genius 3?
My team leader dosent want to disclose that
Sorry
not sure that’s why we take so long ig
don’t work 😭
crazy
Have you tried using QwQ-32B? https://huggingface.co/spaces/Qwen/QwQ-32B-preview
Or DeepSeek’s deep think mode with r1-preview at https://chat.deepseek.com
I mean if they somehow catch you using ai you are disqualified
Oh it’s banned?
They also stopped allowing AI in USAMTS just recently
People were using it too poorly apparently lol
Oh no
I do wonder why they disallow it, if used correctly it’s extremely powerful
aint no way in fuck im doing this
Why? It's not that bad
u do it ._.
After the final quiz were gonna go into 4D and 5D figures
our professor is really smart
oh nvm i got it
$$\left[\frac{\int_0^1 \int_0^2 \int_0^3 (xyz + \cos(x)) dy dx dz}{\int_1^3 \int_2^5 \int_3^7 (xyz + \tan(x)) dy dx dz}\right] = \frac{6 + 6\sin(1)}{144 + 12\ln(\sec(3)) - 12\ln(\sec(1))} = \boxed{\frac{1 + \sin(1)}{24 + 2\ln(\sec(3)) - 2\ln(\sec(1))}}$$
Madchette
holy shit that bot is good
somebody help me ._.
that's nothing
What’s the question I mean
im comprehending the problem till the 3rd statement... Like does it want me to label my vertices in an unordered manner such that it meets the 3rd statement?
my figure's vertices when labeled orderly doesnt meet the 3rd condition, but gets 108 deg as the answer
your CE and BD don't intersect?
Do you guys have any recommended courses for the Mathematical Olympiad?
they do, but constructing a circle that passes through CDGI seems impossible
send your drawing
I think it's because you drew the pentagon to be regular
That probably makes CDGI cyclic impossible
yeah
but it says equiangular pentagon. is it any different?
oh
It might be easier to start with CDGI and reverse engineer the pentagon
yeah
But it's gonna be hard to draw either way
i was thinking of simply makking a circle that passes through CDGI first
then bruteforce both the drawing and the vertices
but upon observation, wont an equiangular pentagon not be regular if and only if the two non adjacent sides (like the left and right sides) are extended?
coz like if I extend the sorta base or roof, it's not equiangular anymore, no?
whaaaa
but for pentagons?
the only way i could think of an equiangular pentagon thats not regular is if 2 non adjacent sides are extended or shrinked
trying to make my drawing (or ways i could draw) easier😭
anyone have a nice combi?
Now you can repeat that operation on different pairs of sides
alternatively draw a 108-36-36 triangle and take isoceles snippets off the ends
which i think? spans all the equiangular pentagons
comp math is scary
My solution:
n x 2^n x 4^n = n x 2^n x 2^2n = n x 2^3n = n x 8^n
8^(2n-72) = 8^n * 8^(n-72)
n = 8^(n-72)
8^72n = 8^n
idk where to go from here tho
n = 0 is really close but idk if "really damn close to 0" is allowed
<@&286206848099549185>
oh nevermind this is so freaking easy
🤣
lol
gang
whats the best strat for like amc 10
do u wanna like sweat out problems 1-13 and not worry about the end
or do the whole thing but risk missing some
revolutionary statement
yeah ....
scores a 105 if u get all those right is that really enough tho?
id say 115 would be ideal 120 ofc is the real goal but still
what have you got so far
(a) 3n == 1 mod 2^k
3n + m2^k = 1
mod 2:
n == 1 hence n is odd
(b)
By Euler’s totient. mod 2^k:
3^phi(2^k) == 1
phi(2^k) = 2^k(1-1/2) = 2^(k-1)
3^2^(k-1) == 1
Hence 3^2^(k-2) is an inverse.
By Hensel’s lifting lemma:
1 is the modular inverse of 3 mod 2^1, so we use the refinement from 2^k to 2^(k+1):
n_(k+1) = n_k - (2 - n_k mod 2^k) mod 2^k
For (c) and (d) I am stuck
I think for (d) they accidentally swapped n and k
otherwise just pick n=2 and you can't find a k that satisfies it
Apparently for (c) and (d) it is supposed to be odd
I suppose the fact that you have hensel's lemma that might be enough to just knock them out
I think that's not enough to fix (c)
Really
well it becomes trivial if that's the fix
k=1
then 1^2 * 9 = 1 mod 2
for all n = 1 mod 2
Wait let me find the corrected version
flipping n and k makes the question make sense to me on both (c) and (d) I'm pretty sure that's the intended meaning
for every positive integer k show there's an n such that 3n=-1 mod 2^k
that would lead to a more natural hensel lifting
that's for d, similarly for c, for each positive integer k, show there's an n such that n^2 is an inverse of 9 mod 2^k - and this would follow from part (b) more naturally as well
see what I mean?
Oh yeah
my mind autocorrected this to them swapping and that's why I made this comment about hensel's lemma
hopefully that doesn't sound totally crazy lmao
imo I think there's an even easier method but I'll keep it secret for now
It’s supposed to lead to this
I was told it’s a troll question that’s why the pointage is so high
smh
it's the collatz conjecture
For n >= 5
well
it should be
Oh
Unsolved problem? Really, it looks so simple
8^2(n-36) because you need to square the 8
so then n=2n-72
n=72
oh oops u got it
bro that is NOT competition
go to #help-32
I don't think that's right, I have already lost faith in the person making this question to not want to continue with it after seeing it's a collatz conjecture question lol
Ok
100 points is mad wt
since (d) isn't my interpretation according to this "correction" I'll just give my solution to my version where for all k show that there is an n such that 3n=-1 mod 2^k
-1/3 = 1/(1-4) = 1+4+4^2+4^3+4^4+... all higher powers of 2 get killed eventually mod 2^k so what's left is the positive integer
this is the geometric series in the 2-adics
Thanks for the help… I have a question, I learnt Hensel’s lifting lemma as geometric series expansion, but then I was told it’s also Newton’s method. I don’t understand, and the Wikipedia page is incomprehensible. Can you help me?
yeah it's the same as Newton's method from calculus as far as how you use it
$$x_{n+1}=x_n-\frac{f(x_n)}{f'(x_n)}$$
Merosity
but you'll have to make sure it satisfies some conditions first
What is the f here
$f(x_0) =0 \mod p$ and $f'(x_0) \ne 0\mod p$
Merosity
a polynomial
Ok
with rational coefficients and denominators not divisible by p
that's just to make sure things stay well defined, there are other versions of Hensel's lemma, but this is a common version to see, we can kind of walk through how to derive it if you haven't seen that
Ok
not the freaky math
the problem's driving my illustrations nuts
, rotate
i got this rough illustration that seem to make sense and got 108deg as the answer (D.) But apparently it must be 72deg (B.)?
It seems like you can’t construct it using a regular pentagon, it really has to be a deformed equiangular pentagon otherwise CDGI cannot be concyclic
So start with the circle and try to construct the pentagon along it
why does <FGH not look = 72deg there either😭
Calculation comes from EFGC and BHGD being cyclic, I am not sure about the parallel lines, I was just looking at my (inaccurate) drawing so don’t trust it
Cyclic is true since <BHD = <BGD = 36 degrees
Hence EGF + BGH = ECF + BDH = 180 - 144 = 36 degrees
FGH = CGB + EGF + BGH = 36 + 36 = 72

Hello everyone
I am in high school and would like to start competition math and maybe start a club with some people
What branches of mathematics are usually relevant in competition math that I should study?
I am currently studying calculus, but I'm not sure how meaningful calculus is in competition math
Algebra, Geometry, Number Theory, Combinatorics
does the imo have college stuff in it
i mean in theory you can kind of do most (if not all (?)) IMO questions with "elementary methods" although some of the "elementary methods" might not be taught in your country until college i.e you are not explicitly taught the euclidean algorithm in the uk unless you take a specific further math module which most people do. read: https://web.evanchen.cc/handouts/Syllabus/Syllabus.pdf
oh thank you so much; that's very helpful
Guys how to solve 3 cos x +2=5
you imagine the unit circle
x can also be 2k*pi radians, where k is any integer
can someone explain this question
Hii
Hi! First calculate the number of unique arrangements without restrictions
then find the number of arrangements that dont satisfy the restriction and take that away from the number of unique ones
We can use complementary counting. Let’s name our events:
A: no 2 S’s consecutive
B: no 2 C’s consecutive
Now, our desired answer counts the number of possibilities within:
A and B
which is logically equivalent to
not (not A or not B)
So now our events are (give it new names for convenience):
C = not A: at least 2 S’s consecutive
D = not B: at least (exactly) 2 C’s consecutive because there are only 2 C’s
The total without restrictions is 7!/(3!2!1!1!) = 420.
Let’s find the count of (C or D) = (C or (D \ C)) = ((C \ D) or D). In this case, since D is simpler, we can probably restrict it more easily, so let’s go with (C or (D \ C)). (You can also use PIE here if you prefer)
C: we need at least 2 S’s consecutive. The keyword “at least” hints at complementary counting. So let’s take the complement.
Total: 420
Bad (no S’s consecutive): first, place all the other letters c,c,e,u with x4!/2! = 12 for ordering. Then place the remaining S’s in 5 spots: .c.c.e.u. (5 choose 3) = 10. So bad = 12x10 = 120.
C = 420 - 120 = 300
(D \ C): exactly 2 C’s consecutive and no S’s consecutive. A similar approach: place cc as a single entity with e and u: cc, e, u so x3! = 6 for ordering. Then .cc.e.u. so for S’s (4 choose 3) = 4.
D\C = 6x4 = 24.
Now the size of (D or C) = 300 + 24 = 324.
Taking the complement, the answer is 420 - 324 = 96.
?
Alternatively, using constructive counting:
place 3 S’s, we need to fill in the middle gaps to be non-consecutive.
.s.s.s.
Let t be a placeholder for e or u (no restrictions) and we will multiply by 2! at the end for permutations.
We will place the c’s first since they have restrictions.
Cases:
Distinct slots
cscs.s x2 for reflection
cs.scs x2 (same calculation as first so we’ll group these)
cs.s.sc
scscs
Same slot:
ctcs.s.s not possible
sctcsts x2
Case 1: cs.scs x4
Fill the gap: .c.st.s.c.s.
then 6 spots for other t
4x6=24
Case 2: cs.s.sc
Fill the gaps, 1 possibility
Case 3: scscs
.s.c.s.c.s.
t in separate slots: 6 choose 2 = 15
t in same slot: 6
(Alternatively, by stars and bars (2+5 choose 5) = (7 choose 2))
6+15=21
So total for distinct slots: 24+1+21=46
Same slot:
Case sctcsts x2 for reflection
2x1=2
Total: 2(46+2)= 96
oh thank you
Got it thanks @vague temple @radiant jasper

For Q14, i cant wrap my head around the idea how ai can form a cyclic Quadrilateral w/ circumcenter O
Hi, which books and websites should I use to prepare for competitions as an A-Level Student
which competitions r u thinking of?
I wonder, how did you get that first equation 180 = 54 + 2x + (36 - y)? I don’t see it
I got the same answer using ADC = AOC = 108
sum of interior angles of triangle BAC
i substituted "y" to <ACB coz i was lazy
since <ACO = 36
Isn’t that the second equation
the 2nd eq is the sum of interior angles of triangle DAC. since <ADC = 54 + x (exterior angle theorem)
Then shouldn’t it read 180 = 54 + 2x + y
I’m not sure how you got that, 36 - y is <OCD
Since AODC is cyclic, ADC and AOC subtend the same arc, so they are equal. Hence AOC = 108 = ADC
I think the problem choices are too easy to guess, it’s very likely to be some multiple of 15 or 18 for these problems since you usually multiply by integer multiples or take complements in 90 or 180 so 18 is the only plausible answer since you start with 54
idek i j wanna get better at maths
oh fair
i grinded out like all of the UKMT maths challenges, that made me quite a bit better at maths
in general for maths, i think you should try focusing on properly understanding some of the content taught in schools
like in school, sometimes they can be quite bad at teaching with emphasis focused on memorisation
which website has like hard a level content
except for madasmaths
or is madasmaths the best
ngl i didn't really do much a level maths revision lol
i just kinda grinded olympiads
but yeah i have heard madasmaths is supposed to be good
when aime cutoff come out
when they are done grading and such
usually its 12/1 isnt it
u reckon i shld j do that
does the AMC 8 include number theory & counting and probability?
Yes
But basic
idek where to put this anymore, this was from a past paper and prob gonna be in my test soon
yr 12 paswt paper
trig ig
did you do the british olympiad training camp
(a) probably just divide the factor out and use quadratic formula
to take square root just set sqrt(z)=a+ib so let z = (a+ib)^2, solve for coefficients
(b)
(i) multiply both sides by (w-1), it becomes the third roots of one
(ii) z2 = wz1
(iii) rotate PR by third rotation so z4 = w(z3-z1) = w(w^2z1-z1)=(1-w)z1
yes
.
just solve problems
that are slightly above ur skill level
Thanks
i do many mocks
should i do jmo practice problems while im still prepping for the aime

Can some plzz solve this
well i mean if ur goal is to just get good at a level maths then probs not
yh
Anyone?
Depends on how well u do on aime
If u just started learning aime stuff probably not but if ur consistently getting like 10,11,12 + it might be worth looking at jmo and oly
I've my maths Olympiad in some days. Can someone guide me where to study and what to practice
This is my syllabus
bruh anyone
distance formula + collinearity moment
how would you get better at like tmua
grind out tmua, grind out MAT, grind out olys etc.
basically just grind maths ig
i think trying to get good at SMC can be quite beneficial for that
bro orz
lol ty
did u make the team
almost
i got to like the final stage (like the top ~10s)
but i didn't quite make the team
but i am on quite a few of the leaderboards
Can i have 10m sb coins
no
Buh
Oh
Did u try this years usamo problems
If you have time try to look at it
💀
@high goblet do u like classical music
If its a high level competition, focus mainly on developing number theory skills and advanced geometry

yh, why?
I can send the sample paper and can then you tell if it's high level or not?
And how can I develop skills on it? Any YouTube channel or playlist recommended

slayy
This is dumb advice
Why only focus on half of the potential problems?
In math olympiads, being good at everything is pretty much always better than being very good at a single topic and mediocre at everything else
fr
DAMN IT JIMMY
I find that number theory is quite flexible and can be helpful for a large range of problems
I might want to get involved in competition math, how difficult is it
For reference I have fairly deep conceptual understandings of algebra and geometry and functions in general, and I learn quickly
depends
on like what level
Like what level of competition math?
Idrk I don't know the levels
then there are more difficult ones like the MOs
what math courses have you taken
I've taken up to algebra 2 but I have a fairly deep understanding of precal and know differential calculus
admits
huh
i think comp math gets much more freaky than normal math classes tho so like you need to read up on combinatronics and some number theory stuff
do the problem i sent
What would you guys rate it on difficulty scale? Is it high level or average or eas
Where
very easy
id say around amc8 level
Nice. Can you tell me how can I practice on similar but a bit difficult problems? Any YouTube playlist, or website with mock tests etc.
artofproblemsolving
google amc8 previous tests
and you will find like 20 tests that are around that level
or you can use the aops free training platforms
like alcumus or mathcounts trainer
aops is the goat for all things math
If it's amc8, practicing higher levels will make them more easy, right?
Okkk. Thanks man
yes
This is my first competition and without anyone to guide so kinda unfamiliar with everything and nervous
mostly the later amc8 problems are on the higher level
compared to the paper you sent me
Okk. What would you ultimately recommend practicing? Sticking to amc8? Or something else
i think amc8 is the best choice
because it has a few more difficult problems
and there are so many to practice on
Okay.
then as you get better and better you can do like amc10, amc12 and aime
Ok
Thanks man.
me completely ignoring every single geometry problem and somehow almost making the UK team
Is there people who are good at a specific topic and not good at generalising
Geometry is basically Pure Mathematics, pure talent required. So does Number Theory.
bro what
Oly geo is extremely niche and pretty much completely divorced from all other math topics
I know lots of people who are extremely good at geo but bad at everything else
and being good at number theory won't help you in a combinatorics problem about snails on a grid
I would argue combinatorics is the topic that “talent” comes into the play the most
But I mean there’s people who are talented with geometry, algebra etc so
Anyway I agree with above
how?
talent means nothing
its about how hard you work
also im a geo main
Talent isn't the most important thing but it can have an impact
no there is talent
a lot of talent
in math
especially higher math
we're talking about comp math
if youre talented and youre motivated then youre obviously going to be really good
but if youre just an average person but youre also motivated you can still be really good
it just matters how much you try
100% true
There are countless people who were "bad at math" before they started doing competitions
It's really just a matter of motivation
yeah I guess that’s true. not something I like as much (I’m not trying to claim I’m very talented it’s just something I think)
What is the socioeconomic status?
If you're from a rich neighborhood, youv have access to better education
When is cutoff released
The math contest education is far more different compared to normal education
But poor people don’t know as much about contests as rich people
And have less access to good tutors bc the cost
But internet helping that
Yaaaa
But u don’t need tutors as much anymore
Thankfully
Imo tutoring isn’t as useful
Yt clutching
As ppl think
AoPS forums:
tutors arent really that useful
cause literally everything is on aops
and there are lots of free sources and you probably can buy a few books
How do u do this: a^2 = 3^b + 37 solve in integers
disagree, tutors provide the face-to-face interaction
otherwise AoPS online classes would have zero demand given the reasons you stated
not everyone does well when self-studying
as if AoPS classes aren't like as much as the opposite of face-to-face. screen to screen not even face to face over screen
but anyway i get what u r saying
exactly so it's even better
The issue with self study is that no one knows how to self study properly
Once they do it goes a lot further tho
there isn't a place to start.
since aops covers so much its rlly hard to just find out what you know and what you don't and where to start
That’s the hardest part
For me personally I’ve gotten a. Lot further self studying
But it’s also because I was more passionate and didn’t have like people forcing me to do stuff I didn’t want to
But it’s probably a case by case thing
Finding what to start with is hard but in general just do more problems a little above ur skill level
idk my skill level bruh
like some times i can go up to question 19 but also don't know how to do question 6
Different categories of math?
Like
Are they different type of questions
i mean there exists talent that allows people to start at a higher level or learn quicker
i think thats undeniable
but yes for sure its not "only" talent and saying that discredits all the hard work that talented people put in
Looking at the graph of y = x^2 and y = 3^x + 37 in the real numbers, we see there are 2 intersections so at most 2 solutions, one positive and one negative.
Now plug in for candidate solutions (estimating the graphs, it should not take too long for exponential to catch up to quadratic):
Positive b:
3^b = 1, 3, 9, 27, 81, ...
We see 27 + 37 = 64 is a perfect square, so (+-8)^2 = (3)^3 + 37 giving (a,b) = (+-8,3).
Negative b:
3^b will be fractional, so a^2 cannot be an integer so a neither.
Hence, (+-8,3) are the only integer solutions.
what?
if you look at the intersections of the graphs x^2 and 3^x+37 you're only getting solutions where a=b
maybe you could find integer points on the elliptic curves y^2=x^3+37, y^2=3x^2+37, and y^2=9x^2+37 then throw out the solutions to x that aren't powers of 3.
clever idea
idk how easy that is, I don't think nagel lutz applies to the other two but I haven't thought about it... also just noticed I put x^2 where I meant x^3 in those 
but that’s wrong
Imo very little is actually talent
Like basically negligible because I know of many people who just spent many hours in math to get better talent doesn’t get you problem solving skills
talent is when you don't need effort, but also you don't need time
time and effort substitute for each other
so yeah, the majority of people had to spend one of those for sure
so talent is "very little" statistically, you can just assume you don't have it, so you're like everyone
where is this problem from?
Me
oh
the answer is if u've cooked up a random problem by urself, then it's highly possible there is no elementary soln
(see like Fermat's Last Theorem or Catalan conjecture lol)
^ sounds like an reasonable approach
idk how to find integer points on elliptic curves, but you can plug those elliptic curves into a database and find all integer points

You can just replace 3^b by x^3?
True, my bad
Using modular arithmetic, I have narrowed down the solutions to:
a = 18n + 8
for some integer n
b = 2m + 1
for some integer m
According to WolframAlpha:
You posted this?
https://math.stackexchange.com/questions/5007345/a2-3b-37
can someone help me make my amc 10 study schedule
Why do you want a study schedule
It's better to explore rather than trying to stick ti a plan
Agreed, if you have no experience then just first list your goals and then try different approaches and record your experiences, then you can decide on which approach to proceed with
because i feel im not learning enough through just exploring the AoPS book
Don’t explore books at first
Do problems
ik the kind of stuffs rhat on amc. I bombed it cause i didn’t study
Then you don't know it
I don't think books are good
For problems
Just find problems in contest collections that look interesting and do them until you have an idea of what contest is like
I have aops books from piracy 💀
i read books when i dont have access to the internet
and sometimes without power
so i like having the books
what does ap calculus course cover?
single variable calc
bc covers up to polar and series
and parametric
I'm currently learning korean curriculum so I'm just confused
like exponent functions and log functions are in pre calc I assume?
like the trignometry function
and then it's ap calc ab?
Exponent functions and log functions are in algebra courses in the usa, and trigonometry is usually covered in precalc
AP Calc AB and AP Calc BC are both taken
They are both year long courses
oh because in korean high school last year
we learn calculus
wait
lemme share a picture
AP Calc AB is a separate course from BC, they share many similarities though, Calc BC just covers more
are stuff like that taught in ab?
Stuff like what?
like things in the image i sent you
that's finding the area covered by a function and its inverse function
ah
it’s possible to show up on a question but highly unlikely
because I'm currently studying in canada
ap calc is very basic imo
and the BC curriculum here is so bad
Yea the AP curriculums arent that good imo
covers less than stewart’s calc did
no not ap like regular math course
oh
like I'm taking pre-calc 11 and they're still working on quadratic function
like the basics of it...
NA education
Yea
LMAO u korean
hi
hi
(That's how I learnt math 😭 )
r u korean?
yeah 😭
yeah that helps
i was scrolling and i saw that
I just learnt from doing competitive math lol
11 and yeah
oh so ur in ap calc course rn i assume?
nah im taking dual enrollment
yeah but I also wanna start working on calc because gpa is more important
what's that
college stuff
GPA is not that much more important imo
oh
Doing well in math contests can get you a lot further than gpa
and it shouldn’t be challenging to balance
but do you know how ap courses work?
yeah but if u cant do well in gpa dont expext to do well in comps lmao
well i know for sure that im not good enough to make it to usamo..
💀
well erm
yeah
my gpa isnt the top but its ok ig
are u good?
But like I do math contests a lot
Yea
sorta
that's all i focus on 💀
did u amo
lol my friend qualified to aime with 0.5% score but got 90% in school math
hm maybe
are you literate in korean by any chance??
I don't want to answer that
yeah
Doing well in school math $\neq$ doing well in contest math
can u dm
stasya
IN math yea
yes
if u got a q hmu
I just
math = free gpa booster
dont know how to write essays LMAO
oh thats fair
i usually write them in like 30 minutes and the teacher gives me like a week or 2
And I just turn in my first draft 💀
senior
i sent ")
