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  3. Ever wondered why ?

Ever wondered why ?

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  • S Single Step Debugger

    lewax00 wrote:

    (a+b)^2 = (a+b)(a+b) = a(a+b) + b(a+b) = a^2 + ab + ab + b^2 = a^2 + 2ab + b^2

    You don’t need this part, it’s more clean without it. Anyway have a five.

    There is only one Vera Farmiga and Salma Hayek is her prophet! Advertise here – minimum three posts per day are guaranteed.

    J Offline
    J Offline
    jschell
    wrote on last edited by
    #21

    Deyan Georgiev wrote:

    ou don’t need this part, it’s more clean without it.

    Try teaching someone who doesn't know how to do that already, without using that step and then see how "clean" it is. Even better try teaching it to 30 people.

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    • A Andy Brummer

      I had a binomial cube[^] in my classroom when I was 4 years old. There are a large number of objects like this that have been part of introducing mathematical concepts to young children as part of Montessori education for close to a hundred years now. Concepts are introduced using multiple senses: vision, touch, weight perception, hearing, etc. once the child becomes familiar with them in an intuitive sense, then the analytic concepts are introduced sometimes years later, but they are usually picked up pretty quickly because the groundwork has already been laid.

      Curvature of the Mind now with 3D

      M Offline
      M Offline
      Michael Bergman
      wrote on last edited by
      #22

      5 for the signature. Very nice.

      m.bergman

      For Bruce Schneier, quanta only have one state : afraid.

      To succeed in the world it is not enough to be stupid, you must also be well-mannered. -- Voltaire

      Honesty is the best policy, but insanity is a better defense. -- Steve Landesberg

      A 1 Reply Last reply
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      • L Lost User

        (a+b)2 = a2 + b2 + 2ab[^] ?

        B Offline
        B Offline
        Bassam Abdul Baki
        wrote on last edited by
        #23

        How did he get a square from a line though? That's the hard part.

        Web - BM - RSS - Math - LinkedIn

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        • A Andy Brummer

          Or even just a visual representation that makes primeness obvious.

          Curvature of the Mind now with 3D

          T Offline
          T Offline
          Tom Clement
          wrote on last edited by
          #24

          Seems like there is such a way, but perhaps not for my brain. Ever read "The man who mistook his wife for a hat" by Oliver Sacks? In it, there are these two autistic twins who alternately recited 6 digit numbers to each other, then, as it dawned on the other that the number was prime, laughed out loud. The twins were separated by our friends at family services. Then there is that high functioning autistic guy "Daniel Tammet", who, in his book "Born on a blue day" tries to tell us about the topological landscape of numbers he sees and explores mentally. Fascinating stuff.

          Tom Clement Serena Software, Inc. www.serena.com articles[^]

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          • T Tom Clement

            Seems like there is such a way, but perhaps not for my brain. Ever read "The man who mistook his wife for a hat" by Oliver Sacks? In it, there are these two autistic twins who alternately recited 6 digit numbers to each other, then, as it dawned on the other that the number was prime, laughed out loud. The twins were separated by our friends at family services. Then there is that high functioning autistic guy "Daniel Tammet", who, in his book "Born on a blue day" tries to tell us about the topological landscape of numbers he sees and explores mentally. Fascinating stuff.

            Tom Clement Serena Software, Inc. www.serena.com articles[^]

            A Offline
            A Offline
            Andy Brummer
            wrote on last edited by
            #25

            I doubt there is. If it was something that was easily recognizable, then it could be turned into an algorithm and there aren't any of those. The only things that I could think of would require an infinite dimensional drawing, so not very useful. I haven't read either of those books, but they are now on my list.

            Curvature of the Mind now with 3D

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            • M Michael Bergman

              5 for the signature. Very nice.

              m.bergman

              For Bruce Schneier, quanta only have one state : afraid.

              To succeed in the world it is not enough to be stupid, you must also be well-mannered. -- Voltaire

              Honesty is the best policy, but insanity is a better defense. -- Steve Landesberg

              A Offline
              A Offline
              Andy Brummer
              wrote on last edited by
              #26

              Thank you. It's a labor of love.

              Curvature of the Mind now with 3D

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              • A Andy Brummer

                I doubt there is. If it was something that was easily recognizable, then it could be turned into an algorithm and there aren't any of those. The only things that I could think of would require an infinite dimensional drawing, so not very useful. I haven't read either of those books, but they are now on my list.

                Curvature of the Mind now with 3D

                T Offline
                T Offline
                Tom Clement
                wrote on last edited by
                #27

                I agree that it could be turned into an algorithm if we really knew what was going on. That's what makes it so intriguing to me :).

                Tom Clement Serena Software, Inc. www.serena.com articles[^]

                1 Reply Last reply
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                • A Andy Brummer

                  I doubt there is. If it was something that was easily recognizable, then it could be turned into an algorithm and there aren't any of those. The only things that I could think of would require an infinite dimensional drawing, so not very useful. I haven't read either of those books, but they are now on my list.

                  Curvature of the Mind now with 3D

                  T Offline
                  T Offline
                  Tom Clement
                  wrote on last edited by
                  #28

                  Here are a few articles on point about autistic savants and prime numbers. http://www.integra.pt/textos/autism.pdf[^] http://goertzel.org/dynapsyc/yamaguchi.htm[^] http://www.scientiareview.org/pdfs/122.pdf[^] All are fascinating.

                  Tom Clement Serena Software, Inc. www.serena.com articles[^]

                  1 Reply Last reply
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                  • L lewax00

                    This one[^] seemed pretty simple.

                    K Offline
                    K Offline
                    krumia
                    wrote on last edited by
                    #29

                    Cool. Not as straightforward as the (a+b)^2 this though :)

                    1 Reply Last reply
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                    • L Lost User

                      (a+b)2 = a2 + b2 + 2ab[^] ?

                      K Offline
                      K Offline
                      krumia
                      wrote on last edited by
                      #30

                      There is a problem with that though. This proof is based on geometry. And geometry, as other branches of maths, are built upon basic postulates. Postulates are just assumptions, that could go wrong. Did you know that there is a strange kind of geometry, in which some of the basic postulates of common (Euclidean) geometry is left out. see this.[^] Actually, I don't know if you can prove this thing in those other geometry or not. :)

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                      • T TheGreatAndPowerfulOz

                        Very nicely explained. I've never seen that before. Give that guy a medal! His accent makes it all the more entertaining.

                        If your actions inspire others to dream more, learn more, do more and become more, you are a leader." - John Quincy Adams
                        You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering” - Wernher von Braun

                        E Offline
                        E Offline
                        Ellen_South_Africa
                        wrote on last edited by
                        #31

                        In South Africa we would say give that man a Bells(as in the whiskey) :) But yeah that's very cool

                        1 Reply Last reply
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                        • S Single Step Debugger

                          lewax00 wrote:

                          (a+b)^2 = (a+b)(a+b) = a(a+b) + b(a+b) = a^2 + ab + ab + b^2 = a^2 + 2ab + b^2

                          You don’t need this part, it’s more clean without it. Anyway have a five.

                          There is only one Vera Farmiga and Salma Hayek is her prophet! Advertise here – minimum three posts per day are guaranteed.

                          B Offline
                          B Offline
                          Brady Kelly
                          wrote on last edited by
                          #32

                          Logically it seems cleaner to me without that as well. My first reaction is a*a, not a*(a+b).

                          1 Reply Last reply
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                          • A AspDotNetDev

                            I wonder if there's a simple visual demonstration of why every even integer greater than 2 can be expressed as the sum of two primes.

                            Thou mewling ill-breeding pignut!

                            G Offline
                            G Offline
                            greldak
                            wrote on last edited by
                            #33

                            much easier to disprove smallest prime 2 so smallest sum of 2 primes = 2+2=4 3 is an integer > 2 3<4 by hypothesis 3 cannot be an integer > 2 contradiction therefore hypothesis is false

                            A 1 Reply Last reply
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                            • G greldak

                              much easier to disprove smallest prime 2 so smallest sum of 2 primes = 2+2=4 3 is an integer > 2 3<4 by hypothesis 3 cannot be an integer > 2 contradiction therefore hypothesis is false

                              A Offline
                              A Offline
                              AspDotNetDev
                              wrote on last edited by
                              #34

                              "even integer", not just "integer".

                              Thou mewling ill-breeding pignut!

                              G 1 Reply Last reply
                              0
                              • A AspDotNetDev

                                "even integer", not just "integer".

                                Thou mewling ill-breeding pignut!

                                G Offline
                                G Offline
                                greldak
                                wrote on last edited by
                                #35

                                oops thats what I get for not reading it properly :(

                                1 Reply Last reply
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                                • L lewax00

                                  Pictures of math don't help me understand it better, I'm better at reasoning through it: (a+b)^2 = (a+b)(a+b) = a(a+b) + b(a+b) = a^2 + ab + ab + b^2 = a^2 + 2ab + b^2 So, (a+b)^2 = a^2 + 2ab + b^2 But I guess that's just how I learn. I'm generally better at objective subjects (math, physics, etc.) than subjective subjects (English, history, etc.) as a result.

                                  G Offline
                                  G Offline
                                  georani
                                  wrote on last edited by
                                  #36

                                  First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                  A J 2 Replies Last reply
                                  0
                                  • K krumia

                                    There is a problem with that though. This proof is based on geometry. And geometry, as other branches of maths, are built upon basic postulates. Postulates are just assumptions, that could go wrong. Did you know that there is a strange kind of geometry, in which some of the basic postulates of common (Euclidean) geometry is left out. see this.[^] Actually, I don't know if you can prove this thing in those other geometry or not. :)

                                    J Offline
                                    J Offline
                                    jsc42
                                    wrote on last edited by
                                    #37

                                    With geometry, you can easily prove that Sqrt(2) = 2.

                                            |            (assume these lines are 1 unit high and 1 unit along)
                                            |
                                            |
                                    

                                    ____________|

                                    The distance between the open ends is sqrt(2) [From Pythagoras's theorem: sqrt(1^2 + 1^2)] 1st approximation of the diagonal:

                                       \_\_\_\_
                                       |    |  Length of diagonal = verticals (1/2 + 1/2) + horizontals (1/2 + 1/2)
                                    

                                    ______| | = 2
                                    | |
                                    |___________|

                                    2nd approximation of the diagonal:

                                          \_\_
                                       \_\_|  |  Length of diagonal = verticals (4 \* 1/4) + horizontals (4 \* 1/4)
                                    \_\_|     |                     = 2
                                    

                                    __| |
                                    |___________|

                                    3rd approximation of the diagonal:

                                         \_,-|  Length of diagonal = verticals (8 \* 1/8) + horizontals (8 \* 1/8)
                                     \_,-'   |                     = 2
                                    

                                    _,-' | (Assume ' represents a small vertical line)
                                    '___________|

                                    (At this stage, I have reached beyond the capability of ASCII art) No matter how many times you do the better approximations of the diagonal, even until the verticals and horizontals are smaller than an atom, the total horizontal distance = 1 and the total vertical distance is also 1, so the diagonal is 2. Therefore, using geometry we have proved that (using Pythagoras's theorem) Sqrt(2) = 2.

                                    K A 2 Replies Last reply
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                                    • G georani

                                      First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                      A Offline
                                      A Offline
                                      Alexander DiMauro
                                      wrote on last edited by
                                      #38

                                      georani wrote:

                                      First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                      Exactly. I learned it without this step. They called it the 'FOIL' method. First Outer Inner Last. (a+b)(a+b) First: a*a Outer: a*b Inner: b*a Last: b*b a^2 + 2ab + b^2

                                      The world is going to laugh at you anyway, might as well crack the 1st joke! My code has no bugs, it runs exactly as it was written.

                                      G L 2 Replies Last reply
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                                      • G georani

                                        First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                        J Offline
                                        J Offline
                                        Jecc
                                        wrote on last edited by
                                        #39

                                        georani wrote:

                                        First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                        Because it's the law! ...the distributive law. With maybe a little commutative on the side.

                                        G 1 Reply Last reply
                                        0
                                        • A Alexander DiMauro

                                          georani wrote:

                                          First you should explain why: (a+b)(a+b) = a(a+b) + b(a+b)

                                          Exactly. I learned it without this step. They called it the 'FOIL' method. First Outer Inner Last. (a+b)(a+b) First: a*a Outer: a*b Inner: b*a Last: b*b a^2 + 2ab + b^2

                                          The world is going to laugh at you anyway, might as well crack the 1st joke! My code has no bugs, it runs exactly as it was written.

                                          G Offline
                                          G Offline
                                          georani
                                          wrote on last edited by
                                          #40

                                          You have not explained it at all. You only showed rules you learnt in school. I think you should show the WHY of these rules.

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