USA | A Nice Algebra Problem | Math Olympiad

Поділитися
Вставка
  • Опубліковано 14 січ 2025

КОМЕНТАРІ • 85

  • @srinivasanlakshminarasimha9282
    @srinivasanlakshminarasimha9282 Місяць тому +7

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

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @antonioatt
    @antonioatt 2 місяці тому +8

    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  2 місяці тому +1

      Very nice! ❤

    • @dan-florinchereches4892
      @dan-florinchereches4892 2 місяці 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 Місяць 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 Місяць тому

      Nice

  • @1234larry1
    @1234larry1 7 годин тому

    The thing that caused me confusion at first was the distribution of 2 when we went from 88 to 176. We present a multiplier of 2 but only distributed it to the -a becoming 2a. It was tricky because when we factor out 2a+1 the final time, we are still left with a factor of 2, but we distribute it across (a+2b) before we subtract 1. If we had subtracted 1 first, then the 1 we subtracted would have been effectively multiplied by 2, which would have been incorrect.

  • @fbj9648
    @fbj9648 Місяць тому +4

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

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @ConradoPeter-hl5ij
    @ConradoPeter-hl5ij 2 місяці 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  2 місяці тому +2

      Very nice solution! I really appreciate that ❤

  • @user-fatfifi
    @user-fatfifi 2 місяці 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)

    • @SALogics
      @SALogics  2 місяці тому +1

      Very nice! ❤

  • @epsom2024
    @epsom2024 Місяць 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)

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @RichieSarabia-ms2er
    @RichieSarabia-ms2er 2 місяці тому +1

    Watching from Philippines sir

    • @SALogics
      @SALogics  2 місяці тому +1

      Thank you so much! ❤

  • @prime423
    @prime423 2 місяці 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 2 місяці тому +1

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

    • @SALogics
      @SALogics  2 місяці тому +1

      Noted! very nice suggession! ❤

  • @epsom2024
    @epsom2024 Місяць тому +1

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

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @davidshen5916
    @davidshen5916 2 місяці 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

    • @SALogics
      @SALogics  2 місяці тому +1

      Very nice! ❤

  • @chao541
    @chao541 Місяць тому +1

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

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @ryanchiang9587
    @ryanchiang9587 2 місяці тому +2

    a = -4, b = -4.

    • @SALogics
      @SALogics  Місяць тому +1

      Yes, you are right! ❤

    • @HeteroComAMaoNaParede
      @HeteroComAMaoNaParede Місяць тому

      No, it's wrong ! a and b must be greater than zero, so a=-4 and b=-4 aren't possible answers

  • @rasulovamahfuza397
    @rasulovamahfuza397 Місяць тому +1

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

    • @SALogics
      @SALogics  Місяць тому +1

      Very Nice! ❤

  • @Sp-A101
    @Sp-A101 Місяць 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

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤

  • @yakupbuyankara5903
    @yakupbuyankara5903 2 місяці тому +1

    (A,B):(2,8)

    • @SALogics
      @SALogics  2 місяці тому +1

      Very nice! ❤

  • @sametsahin2130
    @sametsahin2130 2 місяці тому +1

    44 (mod 12)=8 b=8😊

    • @SALogics
      @SALogics  2 місяці тому +1

      Very nice! ❤

    • @sametsahin2130
      @sametsahin2130 2 місяці 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.

  • @romybaul6053
    @romybaul6053 2 місяці 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  2 місяці тому +2

      Very nice trick! ❤

    • @ramzyalhoofie6666
      @ramzyalhoofie6666 2 місяці тому

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

    • @ronbannon
      @ronbannon 2 місяці тому

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

    • @romybaul6053
      @romybaul6053 2 місяці 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 2 місяці 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 2 місяці тому +1

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

  • @TenguVaran
    @TenguVaran Місяць тому +1

    Зачем так сложно?!
    Ограничили 1

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

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

  • @benjaminchang1382
    @benjaminchang1382 Місяць тому +1

    a shall > 0

  • @gilmendes7319
    @gilmendes7319 2 місяці тому +3

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

    • @SALogics
      @SALogics  2 місяці тому +1

      Oui, tu as raison ! ❤

    • @rabotaakk-nw9nm
      @rabotaakk-nw9nm 2 місяці 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 !!!

  • @carlosterra9287
    @carlosterra9287 Місяць тому +1

    Essa eu achei difícil

    • @SALogics
      @SALogics  Місяць тому +1

      a prática leva à perfeição ❤

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

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

  • @MananArhamOP
    @MananArhamOP 2 місяці тому +4

    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!

  • @genadiyalekseev6630
    @genadiyalekseev6630 Місяць тому +1

    6’23 it’s not correct. If b>0, b may be 0…0.5 and then the right expression will not be greater than the left one

    • @SALogics
      @SALogics  Місяць тому +2

      b > 0 and a positive integer ❤

    • @genadiyalekseev6630
      @genadiyalekseev6630 Місяць тому

      @@SALogics Sorry, I didn't look at the initial conditions. I thought that b-only always positive (but not necessarily an integer)

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

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

    • @SALogics
      @SALogics  2 місяці тому +1

      Hãy tiếp tục học hỏi! ❤

  • @ioannisimansola7115
    @ioannisimansola7115 2 місяці тому +1

    Guessworks

  • @Leleka2310
    @Leleka2310 Місяць тому

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

  • @HarkiratSingh-lg2ng
    @HarkiratSingh-lg2ng Місяць тому +1

    why it cannt be (1,44/3)

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

    Tôi yêu Messi. Cậu ấy làm giáo Viên tốt

    • @SALogics
      @SALogics  2 місяці тому +1

      Messi là ai? ❤

    • @quynhnguyen3873
      @quynhnguyen3873 2 місяці тому

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

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

    Thầy giống Messi quá.

  • @trojanleo123
    @trojanleo123 2 місяці тому +1

    Brilliant!!!

    • @SALogics
      @SALogics  2 місяці тому +1

      Thank you so much! ❤

  • @quynhnguyen3873
    @quynhnguyen3873 2 місяці тому +1

    Nợ mai tính tiếp

  • @簡欽慧
    @簡欽慧 Місяць тому +1

    無聊

    • @SALogics
      @SALogics  Місяць тому +1

      Very nice! ❤