GCD of Polynomials | Number Theory | Korea Junior Math Olympiad 2012 Q4

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  • Опубліковано 10 лют 2025
  • #NumberTheory #Polynomials #MathOlympiad
    I share maths problems and maths topics from well-known contests, exams and also from viewers around the world. Apart from sharing solutions to these problems, I also share my intuitions and first thoughts when I tried to solve these problems.
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    Email me (address in video) your suggestions! lets.think.critically.27@gmail.com

КОМЕНТАРІ • 43

  • @HagenvonEitzen
    @HagenvonEitzen 4 роки тому +20

    Seeing 43 = -7 makes seeing 42² = 49 = -1 easier

  • @chhabisarkar9057
    @chhabisarkar9057 4 роки тому +17

    I'm obsessed with your channel and videos , plz upload more of em including some "floor" function related videos , that would be great !

  • @excited3134
    @excited3134 3 роки тому +2

    FALL IN LOVE WITH UR CHANNEL!! thank for your material which is really helpful for everyone!!! HOPE YOU WILL BE 4EVA here) wish u success !

  • @blankino-1824
    @blankino-1824 4 роки тому +7

    Awesome video and explanation

  • @bosorot
    @bosorot 2 роки тому +1

    Found it easier to do Mod(5) both side . it will concluded that n can be only 1,6,11,16,21 or n=5x+1 form. put it back in equation will get 5^l * 43^m = (5x) * (25x^2 + 15x + 3) . because the primeness .5^l = 5x and 43^m = 25x^2 + 15x + 3

  • @aam2k6
    @aam2k6 3 роки тому +1

    00:00 a legend was born

  • @omaralvarezzaleta4728
    @omaralvarezzaleta4728 4 роки тому +2

    Excelente

  • @aashsyed1277
    @aashsyed1277 3 роки тому

    Awesome explained 👍👍👍👍

  • @sonaraghavan9454
    @sonaraghavan9454 4 роки тому +6

    Superb explanation 👍.

  • @ceooflslam
    @ceooflslam 4 роки тому +5

    Can you kindly explain the line where you took the set of {1,43,-1,-43}mod(25)? What is the process there? Thanks 😊

    • @letsthinkcritically
      @letsthinkcritically  4 роки тому +4

      Those are all the possible values of powers of 43 mod 25

    • @excited3134
      @excited3134 3 роки тому

      @@letsthinkcritically why only 4 numbers are possible?

    • @otakurocklee
      @otakurocklee 3 роки тому +2

      @@excited3134 43^2 is -1 mod 25 (as shown in video). multiply by 43 to get -43 mod 25. Then multiply again by 43 to get 43(-43) mod 25 which is -43^2 mod 25 which is -(-1) mod 25 = 1 mod 25. Multiply by 43 again gives us 43 mod 25, which is the beginning of the cycle.
      So we have a cycle of 43,-1,-43,1 mod 25.

  • @quirtt
    @quirtt 4 роки тому +2

    Nice

  • @AlephThree
    @AlephThree 3 роки тому

    Very nicely explained

  • @exarchoustathees7623
    @exarchoustathees7623 4 роки тому +5

    One small correction this is problem 3 not 4, i think.

  • @particleonazock2246
    @particleonazock2246 3 роки тому

    HK? Yessir.

  • @karthikkrishnaswami3164
    @karthikkrishnaswami3164 3 роки тому +1

    Hi Letsthinkcritically, I am back with my half baked solution :) Can you please guide me as to how move forward with this approach to provide a well rounded solution? By inspection we notice that the parity of n is even. This means n^3-1 divides 215.(this is because l and m are naturals,so the min value of LHS is 215). We notice that n = 6 holds for l=1,m=1. How do I proceed from here and consider other cases and prove that this is the only solution? (using the parity approach)? Please guide

    • @nonamesleft9699
      @nonamesleft9699 3 роки тому

      I think this technique would quickly follow the one done in the video

  • @Deathranger999
    @Deathranger999 3 роки тому

    Are there specifications somewhere for the IMO that state 0 is not in N? Or if you asked a proctor, would they be able to tell you? Most of the time I myself and classes I’ve been in have taken 0 to be a member of N, so I was wondering where the IMO people clarify that.

    • @averyinterestingpineapple6038
      @averyinterestingpineapple6038 2 роки тому

      Natural numbers does not include 0

    • @Deathranger999
      @Deathranger999 2 роки тому

      @@averyinterestingpineapple6038 This is a topic of general disagreement in the mathematical community, and any context in which N comes up should specify which convention is being used.

    • @averyinterestingpineapple6038
      @averyinterestingpineapple6038 2 роки тому

      @@Deathranger999 I know, but I’m fairly confident they exclude 0 for the IMO, at least that’s what I read

    • @Deathranger999
      @Deathranger999 2 роки тому

      @@averyinterestingpineapple6038 Ah, I see. Wonder where that’s stated. Possibly on the cover of the problems.

  • @obaidulkhan9538
    @obaidulkhan9538 3 роки тому

    Please share your story lifestyle

  • @fhffhff
    @fhffhff 3 роки тому

    (1,1,6)

  • @cr1216
    @cr1216 4 роки тому +3

    Wo else thought it was 5^l * 4 * 3^m + 1 = n^3?

  • @piman9280
    @piman9280 2 роки тому

    i am always disappointed when a glaringly obvious solution turns out to be the *only* solution.

  • @mohamedhachi3471
    @mohamedhachi3471 3 роки тому

    I dont inderstand why de have contradiction in the end of this vidéo

    • @fedryfirman.a5783
      @fedryfirman.a5783 3 роки тому

      i think it's because from the last equation in the left that n²+n+1=43^m, and then from contradiction part, n²+n+1=43^m must be 3 mod 25, but we have in the end that 43^m are 1,43,-1, or -43 mod 25, so there's a contradiction and l never be greater or equals to 2

  • @mohamedhachi3471
    @mohamedhachi3471 3 роки тому

    ??

  • @dakcom-mk6mp
    @dakcom-mk6mp 10 місяців тому

    Nice