Solving a 'Stanford' University entrance exam | b=?

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  • Опубліковано 14 січ 2025

КОМЕНТАРІ • 13

  • @amitanshsrivastav9640
    @amitanshsrivastav9640 19 годин тому +1

    B⁶=3⁶
    B⁶-3⁶=0
    (B³)²-(3³)²=0
    (B³+3³)(B³-3³)=0. [A²-B²=(A+B)(A-b)]
    Using a³+b³= (a+b)(a²-ab+b²)
    And a³-b³= (a-b)(a²+ab+b²), we get
    (B+3)(B-3)(B²-3B+9)(B²+3B+9)=0
    So we get B+3=0, B-3= 0 for B= {+3,-3}
    And
    B²-3b+9=0
    a=1, b=-3, c=9
    B = [-b+/-√(b²-4ac)]/2
    B=[-(-3)+/-√((-3)²-4×9)]/2
    B= [3+/-√(9-36)]/2
    B=[3+/-√(-27)]/2
    Since we can't calculate negative square roots, we have to use the complex number i=√-1
    √-27= √(27×-1)
    Using the property √(a×b)= √a√b, we get
    √-27=√27 ×√-1
    √-27=√27i
    So we get two more solutions for B, extending the solution set to=
    {3, -3, (3+√27i)/2, (3-√27i)/2}
    Now solving B²+3B+9=0
    a= 1, b=3, c=9
    B= [-b+/-√(b²-4ac)]/2
    B= [-3+/-√27i]
    Making the final solution set= {3, -3, (3+√27i)/2, (3-√27i)/2, (-3+√27i), (-3-√27i)}
    We could have taken √27 to be 5.2 and simplified more for a simplified but approximate answer, but I let it stay as it is because its depend on the type of question we are solving, say a real life problem will only have the solution +3 and -3 but in a competitive exam, we may require the complex roots.
    Asad, if you see this, pls pin me

  • @willft520
    @willft520 6 годин тому

    It's really easy to overlook the complex solutions by simply inferring b = 3 or b = +- 3. Beautiful exercise!

    • @AsadInternationalAcademy
      @AsadInternationalAcademy  6 хвилин тому

      Totally agree!

    • @AsadInternationalAcademy
      @AsadInternationalAcademy  6 хвилин тому

      Watch 110+ most important olympiad questions with solutions by just clicking on the link below
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  • @arturlukomski6713
    @arturlukomski6713 15 годин тому

    b = 3 😂

  • @mehdizangiabadi-iw6tn
    @mehdizangiabadi-iw6tn 13 годин тому

    b=3

  • @WolfHoll
    @WolfHoll 10 годин тому

    😂! the solution can be seen without calculation! b=3, b=0, b=-3 😂😂😂

    • @amitanshsrivastav9640
      @amitanshsrivastav9640 6 годин тому

      There are 6 solutions to this

    • @AsadInternationalAcademy
      @AsadInternationalAcademy  Хвилина тому

      ok dear

    • @AsadInternationalAcademy
      @AsadInternationalAcademy  Хвилина тому

      Watch 110+ most important olympiad questions with solutions by just clicking on the link below
      ua-cam.com/play/PLybCHBiqtqWP-TrcsG21MXXxlknROi514.html
      Don't forget to share this link with your classmates so that they also have a benefit of it. Please, like and subscribe this channel including pressing bell icon to get the notification of new video!

    • @AsadInternationalAcademy
      @AsadInternationalAcademy  Хвилина тому

      yes dear

  • @gopagon2114
    @gopagon2114 12 годин тому

    b=3