USA | A Nice Algebra Problem | Math Olympiad

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  • Опубліковано 24 лис 2024

КОМЕНТАРІ • 75

  • @srinivasanlakshminarasimha9282
    @srinivasanlakshminarasimha9282 7 днів тому +5

    rearrange the eq to: b = [44-a^2] / [2a + 1]. since both a, b > 0 a

  • @fbj9648
    @fbj9648 5 днів тому +3

    a²+2ab+b²=44+b²-b
    Only b=5 and b=8 give perfect square. Then calculate a.

  • @epsom2024
    @epsom2024 3 дні тому +1

    (2a+1)b=44-a^2>0.a=1,2,3,4,5,6. (a,b)=(2,8),(3,5)

  • @epsom2024
    @epsom2024 3 дні тому +1

    (2a+1)b=44-a^2 . 2a+1>=3
    b=(44-a^2)/(2a+1)=(1/4)*{(-2a+1)+175/(2a+1)}
    (2a+1)(2a+4b-1)=175
    (2a+1,2a+4b-1)=(5, 35),(7, 25)

  • @ConradoPeter-hl5ij
    @ConradoPeter-hl5ij 27 днів тому +1

    (we want to find a p*q=a²+2ab+b; with p and q ∈ N*)
    So, we will star isolating b and a in the equation to find a divisible term after:
    For every b and a, not necessarly in Z:
    a²+2ab+b=44
    a²+b(2a+1)=44
    2a²+a+b(2a+1)=44+a²+a
    a(2a+1)+b(2a+1)=44+a²+a
    (a+b)(2a+1)=44+a²+a
    a+b= [a²+a+44]/(2a+1)
    ● b = {[a²+a+44]/(2a+1)}-a;
    with 2a+1≠0
    But,
    remember b ∈ N*, then:
    make it:
    Q(a)=a²+a+44 and q(a)=2a+1
    then,
    [a²+a+44]/(2a+1)=[Q(a)]/[q(a)]=p(a)
    and p(a)=n, n ∈ N*.
    ///////////////////////////////////////////////////
    finding the p(a) and r(a):
    Q(a) = a² + a + 44 | q(a) =(2a+1)
    -a² - a/2 ||p(a)=(a/2)+(1/4)
    -----------‐
    0 + a/2 + 44
    - a/2 - 1/4
    -------------------
    0 + 175/4 = r(a)
    /////////////////////////////////////////////////
    Constructing p*q into the original equation:
    So,
    Q(a)=q(a)*p(a) + r(a)
    ● a²+a+44=(2a+1)*[(a/2)+(1/4)] +(175/4)
    retake the original equation:
    a²+2ab+b=44
    a²+b(2a+1)=44
    2a²+a+b(2a+1)=44+a²+a
    a(2a+1)+b(2a+1)=44+a²+a
    (a+b)(2a+1)=44+a²+a;
    but remember Q(a)=44+a²+a
    then,
    (a+b)(2a+1)=(2a+1)[(a/2)+(1/4)]+(175/4)
    make 4 times the equation:
    (4a+4b)(2a+1)=(2a+1)[2a+1]+175
    (4a+4b)(2a+1)=(2a+1)²+175
    (4a+b)(2a+1) - (2a+1)² =175
    (2a+1)[(4a+4b)-(2a+1)]=175
    (2a+1)[4a-2a+4b-1]=175
    (2a+1)(2a+4b+1)=175
    Where are the p and q? It is here the term p=(2a+1) and it the term q=[(2a+1)+4b].
    ■(2a+1)[(2a+1)+4b]=175; n=2a+1
    better make like this way:
    ■n(n+4b)=175
    Now, we can thing the possibilites:
    n×(n+4b)=5²×7;
    with
    ■D(175)={1;5;7;25;35;175}
    And
    ■ n ⊂ D(175) (I)
    then,
    n ⊂ {1;5;7;25;35;175}
    //////////////////////////////////////////////////
    Considering the domain of the question:
    remember that n=2a+1 and consider a ∈ N* because the question already said it. And, remember b ∈ N. And think about a domain of a and b.
    So,
    retake a²+2ab+b=44
    you can see that each term of the equation cannot be bigger than 44. Then,

    • @SALogics
      @SALogics  27 днів тому +2

      Very nice solution! I really appreciate that ❤

  • @antonioatt
    @antonioatt 17 днів тому +6

    I like your factorization solution, but I think this can be solved simply in this way(not sure is acceptable for math olympiads): since a>0,b>0 than a^2b=8,a=3=>b=5

    • @SALogics
      @SALogics  17 днів тому +1

      Very nice! ❤

    • @dan-florinchereches4892
      @dan-florinchereches4892 12 днів тому

      I would go in a similar way. Factorizing is a pain in the ass so I would just separate b
      b=(-a^2+44)/(2a+1) |X2
      2b=(-a(2a+1-1)+88)/(2a+1) |X2
      4b+2a=(2a+1-1+176)/(2a+1)
      4b+2a-1=175/(2a+1)
      (4b+2a-1)(2a+1)=175 and from this we can look for all possible positive or negative pairs which can satisfy the equation

    • @азаматхамидов-ы7з
      @азаматхамидов-ы7з 4 дні тому

      a^2+ab+ab+b=44
      a(a+1)+b(a+1)=44
      (a+1)(a+b)=44=4*11 или=2*22 или 1*44, если в целых. Подходит последнее: ответ: a=0, b=44.
      1. а+1=4, a=3,
      a+1)=4, (a+b)=11; ответ: a=3, b=8

    • @DrVanass
      @DrVanass 16 годин тому

      Nice

  • @Sp-A101
    @Sp-A101 7 днів тому +1

    2,8 just by putting a=2 and solving for b, if b comes to be a positive integer, its the correct answer

  • @rasulovamahfuza397
    @rasulovamahfuza397 8 днів тому +1

    4a^2+8ab+4b=176
    4a^2-1+4b(2a+1)=175
    (2a-1)(2a+1)+4b(2a+1)=175

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    a = 0 thì b =44. a khác 0 thì f(a) có nghiệm nguyên dương.

  • @davidshen5916
    @davidshen5916 15 днів тому +1

    A^2+2AB+B=B(2A+1)+A^2-1/4+1/4=(A+1/2)(2B+A-1/2)+1/4=44,(2A+1)(2A+4B-1)=175

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    HƯỚNG LÀ: A.B =0. Hằng đẳng thức. Hoặc phân tích đa thức. Đưa về A.B =0

  • @chao541
    @chao541 7 днів тому +1

    44 is small. Just try A from 1 til 6.

  • @user-fatfifi
    @user-fatfifi 13 днів тому +1

    (a²+2ab+b²)-b²+b=44
    (a+b)²-(b²-b+(1/2)²)+(1/2)²=44
    (a+b)²-(b-1/2)²=44-1/4
    (a+b+b-1/2)(a+b-b+1/2)=175/4
    (a+2b-1/2)(a+1/2)×4=175
    (2a+4b-1)(2a+1)=175=5*5*7*1
    Case1 175*1
    2a+1=1 ,a=0 (X)
    Case2 35*5
    2a+1=5 ,a=2 ,8+4b-1=35 ,b=7
    Case3 25*7
    2a+1=7 ,a=3 ,6+4b-1=25 ,b=5
    (a,b) =(2,7) or =(3,5)

  • @RichieSarabia-ms2er
    @RichieSarabia-ms2er 10 днів тому +1

    Watching from Philippines sir

    • @SALogics
      @SALogics  10 днів тому +1

      Thank you so much! ❤

  • @prime423
    @prime423 Місяць тому +3

    First,dont use a line for division when you are multiplying!!This confuses students.In addition ,this i s much easier solved by trial and error.We know a is limited between 1 and 6.Just try them!!

    • @musicsubicandcebu1774
      @musicsubicandcebu1774 Місяць тому +1

      Re-arrange, isolating b
      b = (44 - a²)/(1 + 2a)
      0 < a < 7

    • @SALogics
      @SALogics  Місяць тому +1

      Noted! very nice suggession! ❤

  • @ryanchiang9587
    @ryanchiang9587 9 днів тому +2

    a = -4, b = -4.

    • @SALogics
      @SALogics  9 днів тому +1

      Yes, you are right! ❤

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    A.B=0. Làm như thế nào. 44 là chỗ khó. MỐI LIÊN HỆ a.b và 24.

  • @sametsahin2130
    @sametsahin2130 10 днів тому +1

    44 (mod 12)=8 b=8😊

    • @SALogics
      @SALogics  10 днів тому +1

      Very nice! ❤

    • @sametsahin2130
      @sametsahin2130 9 днів тому

      @SALogics DEGERLİ dostum tüm üslü sayılar mod la çözülebilir.Bunun çalışmasını yapıyorum .Aslında asal sayılarla ilgilenirken üslü sayılar tesadüfen karşıma çıktı ve logaritma limit trigonometri 10 yaşındaki çocugunn çözebileceği yöntemler buldum.😁😁Örneğin x^3+y^3+z^3=a^3 mü sorusu cevabı irrasyonel olarak vardır.

  • @benjaminchang1382
    @benjaminchang1382 3 дні тому +1

    a shall > 0

  • @yakupbuyankara5903
    @yakupbuyankara5903 10 днів тому +1

    (A,B):(2,8)

  • @Leleka2310
    @Leleka2310 2 дні тому

    Case 1. a=0, but a>0. Nothing

  • @romybaul6053
    @romybaul6053 29 днів тому +2

    If the original equation is transformed into an equation that has the one variable on one side of the equation and the other variable on the opposite side of the equation, we will have: b=(44-a^2)/(2a+1).
    From the above relationship, if we assign any value for "a", we will obtain a corresponding value for "b". Therefore, there are infinitely many pair of solutions for "a" and "b". Examples are: (a,b)=(0,44), (2,8), (3,5), (12,-4), (17,-7), (87,-43), (-1,-43),(-3,-7), (-4,-4), (-13,5), (-18,8), (-88,44) and so on.

    • @SALogics
      @SALogics  28 днів тому +2

      Very nice trick! ❤

    • @ramzyalhoofie6666
      @ramzyalhoofie6666 23 дні тому

      يجب أن تلتزم بأن تكون قيمة كل من a>0 and b

    • @ronbannon
      @ronbannon 19 днів тому

      Okay, that's nice. Thank you for the input; however, there's only a finite number of integral solutions.

    • @romybaul6053
      @romybaul6053 17 днів тому

      @@ronbannon Thanks. I agree with you that there are only a finite number of integer solutions. However, the original problem is presented in a way that it simply asks for a=?, b=?. No restrictions are mentioned beforehand that a, b must be integer values. It is only when you click to play the video will you see the restrictions (a>0 and b>0). As a huge fan of these mathematical puzzles, I always try to solve the problems presented using my own analysis and approach. After I've done that, that's the time I play the video to verify if my answers are correct. Just to refresh you, notice that the original equation presented is actually an equation of a parabola (where the variables "a" and "b" are used instead of "x" and "y" found in analytic geometry textbooks. Since the parabola is a continuous locus of points, there would be an infinite number of points along its curve (unless you impose a restriction on the range and nature of values for "x" and "y".

    • @romybaul6053
      @romybaul6053 17 днів тому

      @@ronbannon Thanks. I agree with you that there are only a finite number of integer solutions. However, the original problem is presented in a way that it simply asks for a=?, b=?. No restrictions are mentioned beforehand that a, b must be integer values. It is only when you click to play the video will you see the restrictions (a>0 and b>0). As a huge fan of these mathematical puzzles, I always try to solve the problems presented using my own analysis and approach. After I've done that, that's the time I play the video to verify if my answers are correct. Just to refresh you, notice that the original equation presented is actually an equation of a parabola (where the variables "a" and "b" are used instead of "x" and "y" found in analytic geometry textbooks. Since the parabola is a continuous locus of points, there would be an infinite number of points along its curve (unless you impose a restriction on the range and nature of values for "x" and "y".

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    Học Toán là Đoàn kết Gia Đình vì Hợp Tự nhiên . KHÁCH QUAN

    • @SALogics
      @SALogics  Місяць тому +1

      Hãy tiếp tục học hỏi! ❤

  • @carlosterra9287
    @carlosterra9287 4 дні тому +1

    Essa eu achei difícil

    • @SALogics
      @SALogics  2 дні тому +1

      a prática leva à perfeição ❤

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    Tôi yêu Messi. Cậu ấy làm giáo Viên tốt

    • @SALogics
      @SALogics  Місяць тому +1

      Messi là ai? ❤

    • @quynhnguyen3873
      @quynhnguyen3873 Місяць тому

      Bạn không yêu Messi à? Cậu ấy là Giáo viên trên sân. Không phải cầu thủ đâu.

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    Thầy giống Messi quá.

  • @gilmendes7319
    @gilmendes7319 Місяць тому +2

    Solution (0 ; b) n'est pas solution dans Z* (a > 0)

    • @SALogics
      @SALogics  Місяць тому +1

      Oui, tu as raison ! ❤

    • @rabotaakk-nw9nm
      @rabotaakk-nw9nm Місяць тому

      ​​@@SALogics😳🤣😡
      a,b є N => a=1,2,3...
      a,b є Z+ => a=0,1,2,3...
      😬 The day before:
      @habeebalbarghothy6320
      Also (a,b)=(0,44) is possible.
      @SALogics. ❤️
      Yes, you are right!❤️
      😂 Verify: 0²+2•0•44+44=44 !!!

  • @MananArhamOP
    @MananArhamOP Місяць тому +3

    The main reason u are not getting support even after such good content is that your channel name is salogic, but if someone searches sa logic, then your channel does not appear, so plz get a better name for your channel related to maths..For example Maths GO!

    • @SALogics
      @SALogics  Місяць тому +1

      Nice suggession! ❤

  • @ioannisimansola7115
    @ioannisimansola7115 20 днів тому +1

    Guessworks

  • @HarkiratSingh-lg2ng
    @HarkiratSingh-lg2ng 7 днів тому +1

    why it cannt be (1,44/3)

  • @quynhnguyen3873
    @quynhnguyen3873 Місяць тому +1

    Nợ mai tính tiếp

  • @trojanleo123
    @trojanleo123 Місяць тому +1

    Brilliant!!!

    • @SALogics
      @SALogics  Місяць тому +1

      Thank you so much! ❤

  • @簡欽慧
    @簡欽慧 День тому

    無聊