#competition-math

1 messages · Page 17 of 1

glad zinc
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Uh oh

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It’s so over 😭

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I “proved” it’s not possible for anything other than 3

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Has anyone heard of the ISMTF Olympiad?

deft wraith
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did you do sine rule way

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what are you thinking for silver and gold medal bounadries 👀

high goblet
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let AM meet circle BPC at point Q then finish

high goblet
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gold will be leaderboard, silver will be just below leaderboard

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how did u do?

vague temple
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I’m not sure but here’s my solution: @hidden oracle

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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.

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Ok so looks like I indeed messed up the graph so the answer is indeed 2 x 1/6 = 1/3

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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)

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Hi everyone, other than AoPS by category, where can I train specific AMC 12/AIME topics individually?

deft wraith
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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)

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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

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im guessing like 2-3 marks max for that lol

deft wraith
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do you lose marks if you state something untrue after

high goblet
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what was ur soln to 6?

high goblet
deft wraith
deft wraith
high goblet
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there's a cute way of doing it with pigeonholes directly

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split ur cube into 8 2x2x2 cubes

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then you can split each of ur 2x2x2 cubes into 2 bits by a 'chessboard' pattern

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and then that basically finishes the problem

deft wraith
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that's quite nice

high goblet
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this was the soln george found when he was very drunk lol

deft wraith
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i did 5 with orders

high goblet
deft wraith
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is this george z

high goblet
deft wraith
# high goblet how?

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

high goblet
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right ic

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well anyway i shall look forwards to marking ur work

deft wraith
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let me know if you spot it or find any funny solutions

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where did people get stuck with 3 is it just a you either spot it or you dont question

hidden oracle
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you misinterpreted it

prisma loom
vague temple
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That's Putnam A6

hidden oracle
solid kindle
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Any idea how to do the first problem

weary light
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135

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from screen'

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to awda

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birngq

misty belfry
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Yeah its 135

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anybody know what this function is?

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The question says: 17) What is the expanded function term?

ornate coyote
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math hurts my brain

shadow spruce
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Pure Mathematics

gusty verge
jade widget
hexed oak
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does anyone know a synthetic proof of the existence of isogonal conjugates?

snow tartan
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What do people think bmo2 qualification mark will be

high goblet
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i heard ppl found it to be a hard year

high goblet
snow tartan
jade widget
hexed oak
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i got a ping here

jade widget
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idk

ornate coyote
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huh

jade widget
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Hi

jade widget
soft vigil
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this is cool

vague temple
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Is there a better way than PIE/casework?
How many distinct five-letter permutations are possible using five of the letters in COMMITTEE?

pallid dragon
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probably not

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it's pretty fast in this case

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well i'm not sure i understand the task

vague temple
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I think casework is slightly simpler

pallid dragon
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you don't need casework or pie

vague temple
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Like 2,2,1,1,1 and 2,2,2,1,1

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Wait really

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How

pallid dragon
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it has MM or TT or EE and never two pairs

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like if a word is MMEEC

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that's using 3 letters

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but they want 4

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oh it was a typo

vague temple
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Yeah I edited it from a mathcounts question and forgot to change the last part

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It was like the same question but 4 letters from MATHCOUNTS

pallid dragon
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i don't see how pie would work, it's two three cases yeah

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one pair or two

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or none

vague temple
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Oh wait it's disjoint I just realized so PIE is not needed

pallid dragon
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pie would be like, 3(words with MM) − 3(words with MM and TT)

vague temple
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Ok

pallid dragon
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but words with MM are hard to count, basically back to square one

vague temple
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I'm tired I'll take a break and try again

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My brain is not processing

warped anvil
radiant jasper
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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?

ornate coyote
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i think the intended solutioon is to separate 1-7 and 8-14

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and then you just continue wiht it

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im not sure what you tried to do

radiant jasper
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But what i did was going from 14 to 8

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So i was wondering how i would figure out to start from 8

ornate coyote
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cancelling from 14 is the right choice

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or the faster one imo

radiant jasper
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But the result comes out differently

ornate coyote
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i think you did it wrong

radiant jasper
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Because cancelling from 14 it’s 1x6x5x …

radiant jasper
ornate coyote
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yeah i dont think you can cancel it like that

radiant jasper
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Why not?

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But if I statt from 8 it works

ornate coyote
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it doesnt work because if yoou start from 14

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lets say 14 pairs with 7, and with 1-6 and 8-13

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you cant just set it up with any combination

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since when going from 6 x 5 x 4 x 3 x 2 x 1 means that any pairs are possible

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but when you start from 8 you wont overcount

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4 x 3 x 3 x 2 x 2

radiant jasper
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Ohh

radiant jasper
ornate coyote
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took me a while to word it out

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not good at explaining math

radiant jasper
normal granite
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what's BMO?

normal granite
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💀 no one does that

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It's the other way around because imo qual for US is way harder

vague temple
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Since we have 3 letters appearing 1 time and 2 letters appearing 2 times, we simply find the coefficient of $x^5$ in $5![(1+x)(1+x+\frac{x^2}{2!})]^3$

gilded haloBOT
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victor

vague temple
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Hopefully no mistake was made

ornate blade
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Jk

vague temple
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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 ??

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Wait what

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Did I mess something up

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Oops

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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

normal granite
ornate coyote
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i think china usually wins overall

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cause yk 4x population

vague temple
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Ok both work very nicely then

radiant jasper
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The china tst is much harder than the imo

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I’d say getting on chinas imo team is more of an accomplishment than getting gold (you’re getting it anyway)

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Like silver medalists and bronze medalists will never get into china’s imo team

normal granite
normal granite
radiant jasper
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No

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I’m not a mopper so my opinion doesn’t matter tho

soft vigil
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wtf are you yapping about

normal granite
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what's the difference between the two

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like difficulty*

ornate coyote
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usamo is like

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miles easier than imo

hearty tendon
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from what ive heard usamo p1>imo1 but imo3>usamo3

ornate coyote
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debatable

soft vigil
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@ornate coyote you should be able to solve this

ornate coyote
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dont we just use a short induction

soft vigil
radiant jasper
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bro what is the question even saying T.T

ornate coyote
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what is the probability that you make a triangle that has all 3 points on the circle

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so basically you can find out how many sets of 3 points you can pick

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to be the vertices of your triangle

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and then place the last segment

hearty tendon
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but usamo is not like a lot easier than imo

radiant jasper
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ok that's a weird question

prisma loom
hearty tendon
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my fault gang

prisma loom
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Well the first part

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The second part is true

hearty tendon
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i can always kill imo1/4 but i sometimes cant do usamo1/4

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so thats what i thought 💀

prisma loom
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Well there are differences in "problem flavor" between contests

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Maybe IMO just suits you better

hearty tendon
vague temple
# soft vigil u sure this is harder than imo p1

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.

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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?

summer tusk
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does any1 know how to do this 😢

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from 27th PMO

glad zinc
shadow spruce
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Pure Mathematics

dull glade
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Hey, is there anyone competing in PMO?

soft vigil
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just do $\sum_{d|n, d\neq n} d$

gilded haloBOT
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buboblakistoni

soft vigil
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$s_{26}(n)$ has the same parity as this

gilded haloBOT
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buboblakistoni

jade widget
deft wraith
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Find all integers $(n, m)$ such that $(10n + 4)^m + 4$ is a perfect square.

gilded haloBOT
deft wraith
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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?

deft wraith
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Taking mod 5, doesn't have any solutions, as I thought. Kind of a troll question

winter sable
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um hi

vague temple
vague temple
# summer tusk

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)

hearty tendon
prisma loom
compact wing
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anyone doing ritangle here?

normal granite
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When’s round 1 and 2

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And what’s the selection like

vague temple
vague temple
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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)

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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

hoary radish
glad zinc
glad zinc
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Second is much harder to qualify than first (at least for me)

shadow spruce
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$x+1=2$

gilded haloBOT
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Aestusy

thorn rune
fading bluff
shrewd girder
jade widget
golden escarp
timber wraith
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I did Q5 and this was my approach

neat ledge
deft wraith
vague temple
# timber wraith

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)

radiant jasper
timber wraith
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27th Philippine Math Olympiad (Qualifying stage)

wooden thorn
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Y'all can you add me to the IMO

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Pls

ornate coyote
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math is hard

radiant jasper
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As long as one doesn't try to understand it

swift imp
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I found British math Olympiad

vague temple
# timber wraith I did Q5 and this was my approach

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

vague temple
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Thanks for sharing

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It seems so complicated at first but with induction it gives a contrastingly elegant result

timber wraith
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but most of the trial and error part can be done mentally

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so yeah, it can be thought of as clearing the denominator

vague temple
deft wraith
golden escarp
ornate blade
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TMUA results out

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how did you guys do?

shadow spruce
compact wing
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this has to be a lie 😭

neat ledge
compact wing
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same

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lowkey can’t do genius 3

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this shit feels like a lottery

neat ledge
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I tried number soup

compact wing
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they cooked this years stage 3

neat ledge
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I got a solution but it doesn't fit the same digit present rule

compact wing
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I finished number soup and triangles but can’t do genius 3

neat ledge
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I feel like I've tried every possible one

compact wing
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na say ong 😭

neat ledge
compact wing
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yo that’s actually insane

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how did you practice

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dam

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do you need 100% for a 9

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mines next year so just tryna get info on this shit

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fucking he’ll

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hell

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dam

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that’s actually sick dude well done

gusty verge
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Jk, But fr good job

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I haven't seen the paper, I tutored someone TMUA tho, not sure what they got

high goblet
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not even full marks smh

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anyway gj tho!

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u applying ox?

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ic ic

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which college?

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ic

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well gl with ur application process!

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oxford still haven't sent out interview offers right?

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oh fairs

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how did the MAT go for u then?

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fairs

summer granite
ornate blade
ornate blade
summer granite
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?

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whats that

summer granite
ornate blade
summer granite
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i got 50/45 im too good

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tbh i have no clue what it is

glad zinc
high goblet
summer granite
high goblet
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ah nice

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gj on finishing stage 3!

compact wing
summer granite
compact wing
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oh shit did you do it by code?

summer granite
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He'll no

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That will take ages and I don't really know how to code

compact wing
#

ohh fairs so you guys solved everything already?

summer granite
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a code for the QRS

summer granite
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That's like a whole week

compact wing
#

tf

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so you guys solved everything on Friday?

summer granite
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Yes

summer granite
compact wing
#

4 hours?

summer granite
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No 8

compact wing
#

oh

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tf

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dayum just to confirm what school is this?

summer granite
#

St Gregory's

compact wing
#

dam never heard of it

summer granite
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Yh

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Idk what the sixth-form is called lol

compact wing
#

dawg 😭

summer granite
#

It's like St Catherine

summer granite
summer granite
compact wing
#

dayum how many people are in your team?

summer granite
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5

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How about you

compact wing
summer granite
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Yh

summer granite
compact wing
compact wing
summer granite
compact wing
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guess il at least get an honourable mentions or sum

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genuinely can’t figure this shit out

summer granite
compact wing
summer granite
compact wing
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but can’t figure out from there

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guess gotta do it by hand

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this shit long tho

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might as well give up

summer granite
compact wing
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that’s how we solved all of the puzzles so far so we thought it would work 😭

compact wing
#

yeah

summer granite
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I guess PQRS too

compact wing
#

yup 😭

summer granite
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Technically you could have entered stage 3 without pqrs

compact wing
#

oh yeah maybe but

summer granite
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It's literally in the name

compact wing
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am assuming there’s a limit on the amount of answers

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you can submit

summer granite
summer granite
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We were super careful lol

compact wing
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wait are you guys in year 12 or 13

summer granite
#

12

compact wing
#

dam

summer granite
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Can 13 participate?

compact wing
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I think so?

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but it doesn’t matter to them I think

summer granite
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Oh arl

compact wing
#

applications already ended

summer granite
compact wing
#

uni applications

summer granite
#

Fair

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I was about to say they can put it in their personal statement

summer granite
#

Took a few hours

compact wing
#

oh fairs

summer granite
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Apparently we need working out

compact wing
#

yeah

summer granite
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But I can't find them

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It's on WhatsApp

compact wing
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wdym you can’t find them

summer granite
compact wing
#

oh

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thought you can just have a digital copy

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are you guys sure your gonna be the winning team?

summer granite
#

Still a possibility never know

compact wing
#

dam alright

summer granite
compact wing
#

oh yeah fuc

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never seen an international team win it tho

summer granite
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Yh we are done for

summer granite
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Can't lie I have no working out for modulus graph

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Just used desmos

compact wing
#

I mean that’s appropriate use of technology so it should be fine

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did you guys already like pre learn further maths and stuff

summer granite
#

But I know some stuff

compact wing
#

what did you guys do for like question 26 then

summer granite
#

Already completed a chapter we are not ment to do

summer granite
compact wing
#

the probability one

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one of our mates had to use like a further maths topic to do it

summer granite
#

Ah u use integration

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Ik the basics of it

compact wing
#

yeah

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ohh fairs

summer granite
#

We made a 1x1 square and did like integration or something like that

compact wing
#

could you give any tips for genius 3?

summer granite
#

Sorry

compact wing
#

fairs

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it’s cool

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just gonna do it by hand now then

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fuck coding

summer granite
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Bro don't code that

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How are you even ment to start

compact wing
#

not sure that’s why we take so long ig

summer granite
#

Use chat gpt or something lol

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Ai ain't great tho

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Plus don't think it's allowed

compact wing
summer granite
vague temple
summer granite
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I mean if they somehow catch you using ai you are disqualified

vague temple
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Oh it’s banned?

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They also stopped allowing AI in USAMTS just recently

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People were using it too poorly apparently lol

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I do wonder why they disallow it, if used correctly it’s extremely powerful

misty belfry
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aint no way in fuck im doing this

gusty verge
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Why? It's not that bad

misty belfry
#

u do it ._.

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After the final quiz were gonna go into 4D and 5D figures

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our professor is really smart

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oh nvm i got it

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$$\left[\frac{\int_0^1 \int_0^2 \int_0^3 (xyz + \cos(x)) dy dx dz}{\int_1^3 \int_2^5 \int_3^7 (xyz + \tan(x)) dy dx dz}\right] = \frac{6 + 6\sin(1)}{144 + 12\ln(\sec(3)) - 12\ln(\sec(1))} = \boxed{\frac{1 + \sin(1)}{24 + 2\ln(\sec(3)) - 2\ln(\sec(1))}}$$

gilded haloBOT
#

Madchette

misty belfry
#

holy shit that bot is good

misty belfry
#

somebody help me ._.

prisma loom
#

that's nothing

jade widget
#

What’s the question I mean

jade widget
timber wraith
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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?

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my figure's vertices when labeled orderly doesnt meet the 3rd condition, but gets 108 deg as the answernootlikethis

prisma loom
manic quarry
#

Do you guys have any recommended courses for the Mathematical Olympiad?

timber wraith
prisma loom
#

send your drawing

timber wraith
#

u may ignore the circle

prisma loom
#

I think it's because you drew the pentagon to be regular

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That probably makes CDGI cyclic impossible

timber wraith
#

but it says equiangular pentagon. is it any different?

prisma loom
#

Yes

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You can have non-regular equiangular pentagons

timber wraith
#

oh

prisma loom
timber wraith
#

oohh

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damn

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right

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i didnt visualize the equiangular pentagon like that

prisma loom
#

It might be easier to start with CDGI and reverse engineer the pentagon

timber wraith
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yeah

prisma loom
#

But it's gonna be hard to draw either way

timber wraith
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i was thinking of simply makking a circle that passes through CDGI first

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then bruteforce both the drawing and the vertices

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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?

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coz like if I extend the sorta base or roof, it's not equiangular anymore, no?

ornate blade
timber wraith
#

whaaaa

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but for pentagons?

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the only way i could think of an equiangular pentagon thats not regular is if 2 non adjacent sides are extended or shrinked

timber wraith
hexed oak
#

anyone have a nice combi?

winter sable
#

i hope everyone remembers me

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dx / dy

vague temple
hearty tendon
#

which i think? spans all the equiangular pentagons

ornate coyote
#

comp math is scary

deft siren
#

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

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n = 0 is really close but idk if "really damn close to 0" is allowed

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<@&286206848099549185>

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oh nevermind this is so freaking easy

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🤣

ornate coyote
#

lol

cloud basin
#

gang

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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

cloud basin
cloud basin
cloud basin
#

id say 115 would be ideal 120 ofc is the real goal but still

trim bramble
#

1-15 make sure

#

then find easy 16-25 to do

vague temple
jolly solstice
vague temple
#

(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

jolly solstice
#

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

vague temple
#

Apparently for (c) and (d) it is supposed to be odd

jolly solstice
#

I suppose the fact that you have hensel's lemma that might be enough to just knock them out

jolly solstice
vague temple
#

Really

jolly solstice
#

well it becomes trivial if that's the fix

#

k=1

#

then 1^2 * 9 = 1 mod 2

#

for all n = 1 mod 2

vague temple
#

Wait let me find the corrected version

jolly solstice
#

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?

vague temple
#

Oh yeah

jolly solstice
#

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

vague temple
#

It’s supposed to lead to this

#

I was told it’s a troll question that’s why the pointage is so high

jolly solstice
#

smh

vague temple
#

k > 2

#

That’s the correction

jolly solstice
#

it's the collatz conjecture

vague temple
#

For n >= 5

vague temple
#

Unsolved problem? Really, it looks so simple

terse canyon
#

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

jolly solstice
# vague temple That’s the correction

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

vague temple
#

Ok

terse canyon
#

100 points is mad wt

jolly solstice
#

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

vague temple
#

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?

jolly solstice
#

yeah it's the same as Newton's method from calculus as far as how you use it

#

$$x_{n+1}=x_n-\frac{f(x_n)}{f'(x_n)}$$

gilded haloBOT
#

Merosity

jolly solstice
#

but you'll have to make sure it satisfies some conditions first

vague temple
#

What is the f here

jolly solstice
#

$f(x_0) =0 \mod p$ and $f'(x_0) \ne 0\mod p$

gilded haloBOT
#

Merosity

jolly solstice
#

a polynomial

vague temple
#

Ok

jolly solstice
#

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

vague temple
#

Ok

ornate coyote
#

not the freaky math

timber wraith
timber wraith
gilded haloBOT
timber wraith
#

i got this rough illustration that seem to make sense and got 108deg as the answer (D.) But apparently it must be 72deg (B.)?

vague temple
#

So start with the circle and try to construct the pentagon along it

vague temple
timber wraith
#

why does <FGH not look = 72deg there either😭

vague temple
#

IDK my drawing is horrible

#

Angles are not 108 degrees I didn’t measure

vague temple
# vague temple

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

jade widget
jade widget
#

Have u guy receive the amc score?

#

My friend said her friend got it

zealous fulcrum
#

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

radiant jasper
iron terrace
#

does the imo have college stuff in it

deft wraith
iron terrace
ornate coyote
#

imagine making imo

#

could never be me

plush abyss
#

Guys how to solve 3 cos x +2=5

pallid dragon
#

you imagine the unit circle

ornate coyote
#

cosx=1

#

so x=0

lavish scaffold
#

x can also be 2k*pi radians, where k is any integer

minor matrix
#

Cos(x+2kpi)

#

man trigonometry was a long time ago

#

i nearly forgot everything

ornate blade
#

gahhhh this is the solution, q6

barren sparrow
#

can someone explain this question

hybrid vessel
#

Hii

radiant jasper
#

then find the number of arrangements that dont satisfy the restriction and take that away from the number of unique ones

vague temple
# barren sparrow can someone explain this question

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.

winter sable
#

?

vague temple
#

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

barren sparrow
#

Got it thanks @vague temple @radiant jasper

jade widget
timber wraith
#

For Q14, i cant wrap my head around the idea how ai can form a cyclic Quadrilateral w/ circumcenter O

gilded haloBOT
timber wraith
#

got this

fervent ember
#

Hi, which books and websites should I use to prepare for competitions as an A-Level Student

high goblet
vague temple
# timber wraith

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

timber wraith
#

i substituted "y" to <ACB coz i was lazy

#

since <ACO = 36

vague temple
timber wraith
vague temple
#

Then shouldn’t it read 180 = 54 + 2x + y

#

I’m not sure how you got that, 36 - y is <OCD

timber wraith
#

oh wait right

#

yeah i missed that

#

how did u get <ADC = 108?

vague temple
#

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

fervent ember
high goblet
#

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

fervent ember
#

which website has like hard a level content

#

except for madasmaths

#

or is madasmaths the best

high goblet
#

i just kinda grinded olympiads

high goblet
jaunty orchid
#

when aime cutoff come out

prisma loom
jaunty orchid
#

usually its 12/1 isnt it

prisma loom
#

they'll probably be out soon

#

check aops forums

fervent ember
iron terrace
#

does the AMC 8 include number theory & counting and probability?

iron terrace
#

ah okay

#

thanks

tacit knoll
#

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

radiant jasper
jade widget
#

How to prepare for aime?

#

Just solving problems?

vague temple
# tacit knoll

(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

swift imp
#

.

#

just solve problems

#

that are slightly above ur skill level

ornate coyote
#

i do many mocks

#

should i do jmo practice problems while im still prepping for the aime

jade widget
radiant jasper
#

Can some plzz solve this

high goblet
radiant jasper
swift imp
#

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

dull glade
#

I've my maths Olympiad in some days. Can someone guide me where to study and what to practice

radiant jasper
ivory ember
#

distance formula + collinearity moment

fervent ember
high goblet
#

basically just grind maths ig

#

i think trying to get good at SMC can be quite beneficial for that

radiant jasper
high goblet
#

lol ty

radiant jasper
#

did u make the team

high goblet
#

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

radiant jasper
#

Can i have 10m sb coins

high goblet
#

no

radiant jasper
#

Buh

radiant jasper
#

Did u try this years usamo problems

high goblet
#

nah i don't really look at USAMO

#

i have enough of my own work to do lol

radiant jasper
#

If you have time try to look at it

ornate coyote
swift imp
#

@high goblet do u like classical music

radiant jasper
jade widget
high goblet
dull glade
jade widget
swift imp
prisma loom
#

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

novel karma
#

fr

ornate coyote
#

DAMN IT JIMMY

lavish scaffold
radiant jasper
#

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

ornate coyote
#

on like what level

radiant jasper
ornate coyote
#

yeah

#

there are simpler ones like amc10-aime early questions

radiant jasper
#

Idrk I don't know the levels

ornate coyote
#

then there are more difficult ones like the MOs

ornate coyote
radiant jasper
ornate coyote
#

try taking like an amc10 mock test

#

or like an aime

radiant jasper
ornate coyote
#

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

radiant jasper
#

I hate number theory

#

💀

#

Combinatronjcs tho 🤤

acoustic nova
dull glade
radiant jasper
ornate coyote
#

id say around amc8 level

dull glade
# ornate coyote very easy

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.

ornate coyote
#

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

dull glade
dull glade
dull glade
#

This is my first competition and without anyone to guide so kinda unfamiliar with everything and nervous

ornate coyote
#

mostly the later amc8 problems are on the higher level

#

compared to the paper you sent me

dull glade
ornate coyote
#

because it has a few more difficult problems

#

and there are so many to practice on

dull glade
#

Okay.

ornate coyote
#

then as you get better and better you can do like amc10, amc12 and aime

high goblet
shadow spruce
#

Geometry is basically Pure Mathematics, pure talent required. So does Number Theory.

prisma loom
#

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

deft wraith
#

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

radiant jasper
#

talent means nothing

#

its about how hard you work

#

also im a geo main

prisma loom
#

Talent isn't the most important thing but it can have an impact

acoustic nova
#

a lot of talent

#

in math

#

especially higher math

radiant jasper
#

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

prisma loom
#

There are countless people who were "bad at math" before they started doing competitions

#

It's really just a matter of motivation

acoustic nova
radiant jasper
#

YES

#

LMAO

vapid herald
#

What is the socioeconomic status?

radiant jasper
#

If you're from a rich neighborhood, youv have access to better education

sturdy viper
#

When is cutoff released

swift imp
#

But poor people don’t know as much about contests as rich people

radiant jasper
#

But internet helping that

swift imp
#

But u don’t need tutors as much anymore

radiant jasper
swift imp
#

Imo tutoring isn’t as useful

radiant jasper
#

Yt clutching

swift imp
#

As ppl think

swift imp
ornate coyote
#

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

acoustic nova
#

How do u do this: a^2 = 3^b + 37 solve in integers

ornate blade
#

otherwise AoPS online classes would have zero demand given the reasons you stated

#

not everyone does well when self-studying

acoustic nova
hearty tendon
#

💀

marble grove
#

guy i got a 58!!!

#

i think

#

maybe it was a 52.5 or sum

#

or a 50.5

#

idk

swift imp
#

Once they do it goes a lot further tho

marble grove
#

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

swift imp
#

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

marble grove
#

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

swift imp
#

Like

#

Are they different type of questions

deft wraith
#

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

vague temple
# acoustic nova How do u do this: a^2 = 3^b + 37 solve in integers

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.

prisma loom
#

if you look at the intersections of the graphs x^2 and 3^x+37 you're only getting solutions where a=b

jolly solstice
#

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.

ornate blade
#

clever idea

jolly solstice
#

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 catshrug

swift imp
#

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

pallid dragon
#

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

high goblet
acoustic nova
high goblet
#

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)

high goblet
#

idk how to find integer points on elliptic curves, but you can plug those elliptic curves into a database and find all integer points

jade widget
vague temple
vague temple
#

According to WolframAlpha:

vague temple
low fiber
#

can someone help me make my amc 10 study schedule

swift imp
#

It's better to explore rather than trying to stick ti a plan

vague temple
#

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

low fiber
swift imp
#

Do problems

low fiber
#

ik the kind of stuffs rhat on amc. I bombed it cause i didn’t study

swift imp
#

Then you don't know it

swift imp
#

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

ornate coyote
#

i get mine secondhand from a moper i know

swift imp
ornate coyote
#

i read books when i dont have access to the internet

#

and sometimes without power

#

so i like having the books

radiant jasper
#

what does ap calculus course cover?

valid socket
#

bc covers up to polar and series

#

and parametric

radiant jasper
#

like exponent functions and log functions are in pre calc I assume?

#

like the trignometry function

#

and then it's ap calc ab?

swift imp
#

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

radiant jasper
#

oh because in korean high school last year

#

we learn calculus

#

wait

#

lemme share a picture

swift imp
#

AP Calc AB is a separate course from BC, they share many similarities though, Calc BC just covers more

radiant jasper
radiant jasper
swift imp
radiant jasper
swift imp
#

Area under the curve?

#

That is taught in AB and BC

radiant jasper
#

that's finding the area covered by a function and its inverse function

swift imp
#

Maybe

#

I don't really remember my AP Calc course

radiant jasper
#

ah

valid socket
radiant jasper
#

because I'm currently studying in canada

valid socket
#

ap calc is very basic imo

radiant jasper
#

and the BC curriculum here is so bad

swift imp
#

Yea the AP curriculums arent that good imo

valid socket
#

covers less than stewart’s calc did

radiant jasper
#

no not ap like regular math course

swift imp
#

oh

radiant jasper
#

like I'm taking pre-calc 11 and they're still working on quadratic function

#

like the basics of it...

valid socket
#

NA education

hearty tendon
swift imp
#

Stay ahead

#

Just learn from aops problems lol

radiant jasper
hearty tendon
#

hi

swift imp
#

(That's how I learnt math 😭 )

radiant jasper
#

r u korean?

hearty tendon
#

yeah 😭

radiant jasper
hearty tendon
#

i was scrolling and i saw that

radiant jasper
#

what grade r u in??

#

have you taken ap calc ab?

swift imp
hearty tendon
radiant jasper
#

oh so ur in ap calc course rn i assume?

hearty tendon
#

nah im taking dual enrollment

radiant jasper
radiant jasper
hearty tendon
#

college stuff

swift imp
radiant jasper
swift imp
#

Doing well in math contests can get you a lot further than gpa

valid socket
#

and it shouldn’t be challenging to balance

radiant jasper
#

but do you know how ap courses work?

hearty tendon
radiant jasper
hearty tendon
#

💀

hearty tendon
swift imp
#

my gpa isnt the top but its ok ig

radiant jasper
#

do you know the korean math curriculum?

hearty tendon
swift imp
#

But like I do math contests a lot

hearty tendon
#

at math

#

comps

swift imp
#

Yea

hearty tendon
swift imp
#

that's all i focus on 💀

hearty tendon
#

did u amo

radiant jasper
swift imp
radiant jasper
swift imp
#

I don't want to answer that

hearty tendon
swift imp
radiant jasper
gilded haloBOT
#

stasya

hearty tendon
#

😭

swift imp
radiant jasper
hearty tendon
swift imp
#

I just

radiant jasper
#

math = free gpa booster

swift imp
#

dont know how to write essays LMAO

hearty tendon
swift imp
#

And I just turn in my first draft 💀

hearty tendon
#

lwk same but i bs a lot

#

what grade are u

swift imp
#

senior

hearty tendon
#

o cool

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i tried gridning mop once and bombed jmo

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😭

radiant jasper
swift imp
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amc 10 kinda bad ngl