When is p^2-p+1 a Cube? | Balkan MO 2005

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  • Опубликовано: 13 дек 2024

Комментарии • 23

  • @cassidoodledookevorkian274
    @cassidoodledookevorkian274 2 года назад +6

    Always the best math vids on RUclips 👍

  • @richardfredlund8846
    @richardfredlund8846 Год назад +1

    Amazing .. I love the way the logic flows.

  • @victorchoripapa2232
    @victorchoripapa2232 2 года назад +2

    Wowow... Nice exercise

  • @mathcanbeeasy
    @mathcanbeeasy 2 года назад +3

    This is art. 🥰

  • @Manisphesto
    @Manisphesto 2 года назад +5

    Why do questions like the shape cube instead of x³?

  • @cassidoodledookevorkian274
    @cassidoodledookevorkian274 2 года назад +1

    🔥🔥

  • @JohnWick-hj4ep
    @JohnWick-hj4ep 2 года назад +4

    Amazing! However i have a question if anyone could answer. I was able to follow most of it, but didn't understand how he chose the 2 close perfect squares, around 4:50 - 6:27.
    P.s tips about how to improve would also help :D

    • @Leardakhan3
      @Leardakhan3 2 года назад +2

      I think the strategy is to look at the higher order terms, since there is a^4 - 6a^2, he looked for (a^2 - 3)^2, then you can look for which values of a the linear term and the constant are higher or lower than each other, that is my take at least.

    • @bait6652
      @bait6652 2 года назад

      Radic has to be a square dictated by the 2 Pn terms of highest power.
      Its a bounding trick he often uses when Pn w/o sq repr. has to be square. Bound it to 2-3 values or soln doesnt exist. Look for his n^4 problems ...theres like 3 of them

    • @bosorot
      @bosorot 2 года назад +1

      To make you feel better this is standard olympic math technique. No normal kids can think how to do this on the spot for the first time. They learnt and practice and practice ... . If you can do this technique invented on your own , then you are a genius .

  • @drynshock1
    @drynshock1 6 месяцев назад

    How would you choose the squares if you got something like m^4 + 3m^3 + ... with the cubic term

  • @bowlteajuicesandlemon
    @bowlteajuicesandlemon Год назад

    How do we know that if p divides (x²+x+1), then a factor of p-1 doesn't also divide (x²+x+1) which would mean (x-1) doesn't have to be divisible by p-1?

    • @saadhaider9576
      @saadhaider9576 10 месяцев назад

      Because p-1 = (x^2+x+1) * ((x-1)/p)
      Since (x-1)/p is an integer, x^2+x+1 divides p-1

  • @jpolowin0
    @jpolowin0 2 года назад +2

    I suppose that 1 isn't counted as a prime. :-)

    • @alessiodaniotti264
      @alessiodaniotti264 2 года назад +4

      the definition of prime is based on non trivial divisibility/factorization, so unitary elements are never primes.

  • @piman9280
    @piman9280 2 года назад +1

    It's a short exercise to see that p = 19 produces 343, which is 7^3. Once again we have a problem whose only solution can be found by very simple mathematics. I still enjoyed the robust solution.

  • @johns.8246
    @johns.8246 2 года назад +1

    So how about when is p^2-p-1 a cube? There's at least one obvious solution.

  • @lo-fi_community
    @lo-fi_community 2 года назад +1

  • @harris5140
    @harris5140 2 года назад +1

    p=1 doesn't work? why?

    • @quanquin3822
      @quanquin3822 2 года назад +2

      1 is not prime.

    • @10names55
      @10names55 2 года назад +1

      You ment why not x=1
      Well p^2-p is always >0

  • @와우-m1y
    @와우-m1y 2 года назад +1

    asnwer=1 os isit 🤣🤣🤣🤣

  • @DontStudy
    @DontStudy 2 года назад

    N9