A quick number problem!

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  • Опубліковано 11 вер 2024
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КОМЕНТАРІ • 17

  • @KorlinAng-bs7rh
    @KorlinAng-bs7rh Місяць тому +4

    Alternatively, you may start with p^2 = n-1, then it will lead to the same but slightly easier solution.🤩

    • @JPiMaths
      @JPiMaths  Місяць тому

      Nice, yes this is essentially the same, but saves the awkwardness of writing sqrt(n-1) a bunch of times

  • @santiagoabregu9561
    @santiagoabregu9561 Місяць тому +1

    Nice video

  • @thomaskember3412
    @thomaskember3412 Місяць тому

    I could see at a glance that n must be 1 + a perfect square, also called a square number.

  • @samueldeandrade8535
    @samueldeandrade8535 Місяць тому +1

    My Euler, writing n+5 as √(n-1)√(n-1)+6? Is this some kind of joke ... ?

    • @kmyc89
      @kmyc89 Місяць тому

      The Indian fellas have a specific way of abstraction

  • @MrGeorge1896
    @MrGeorge1896 Місяць тому

    Starting with (n + 5) / sqrt(n - 1) = k and so n + 5 = sqrt(n - 1) k we square both sides and get:
    n² + 10n -k²n +k² = -25
    (n- k² + 11) (n - 1) = -36
    (k² - n - 11) (n - 1) = 36
    So to divide 36 by (n - 1) n must be 2, 3, 4, 5, 7, 10, 13, 19 or 37. But k² must also be a perfect square, so only n = 2 (k² = 49), n =5 (k² = 25), n = 10 (k² = 25) and n = 37 (k² = 49) solves the equation.

  • @samueldeandrade8535
    @samueldeandrade8535 Місяць тому

    0:29 a rational number? Man ... *rolling eyes*

  • @thomaslangbein297
    @thomaslangbein297 Місяць тому

    Much more interesting would be: find all n element R that lead to the quotient being element N.

    • @samueldeandrade8535
      @samueldeandrade8535 Місяць тому

      Yep. The answer is
      2n = m²-20±m√(m²-24)
      for all integer m, m≥5. Right?

  • @JOSHUVASRINATH
    @JOSHUVASRINATH Місяць тому

    Nice ❤

    • @JPiMaths
      @JPiMaths  Місяць тому

      @@JOSHUVASRINATH gracias!

  • @TypoKnig
    @TypoKnig Місяць тому

    Only one of those n values produces an integer for the initial expression, the rest produce rationals, if my mental arithmetic is working this morning

    • @JPiMaths
      @JPiMaths  Місяць тому +2

      @@TypoKnig I don't think your mental arithmetic was working this morning 😂😅

    • @TypoKnig
      @TypoKnig Місяць тому +1

      @@JPiMaths You’re right - I was wrong. No more math before my caffeine kicks in!

    • @JPiMaths
      @JPiMaths  Місяць тому +2

      @@TypoKnig 😂😂😂