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The New Coffee Room

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  3. Puzzle Time - polynomials

Puzzle Time - polynomials

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  • jon-nycJ Offline
    jon-nycJ Offline
    jon-nyc
    wrote on last edited by
    #1

    Find natural numbers x, y, z such that

    x/(y+z) + y/(x+z) + z/(x+y) = 4 .

    Only non-witches get due process.

    • Cotton Mather, Salem Massachusetts, 1692
    1 Reply Last reply
    • KlausK Offline
      KlausK Offline
      Klaus
      wrote on last edited by Klaus
      #2

      35,132,627 seems to be close. I didn't think of course.

      image.png

      Edit: OK, that's not the solution. It's only close.

      There are no solutions in the range 1 to 10,000, even though 411 812 4601 is really close!

      1 Reply Last reply
      • jon-nycJ Offline
        jon-nycJ Offline
        jon-nyc
        wrote on last edited by jon-nyc
        #3

        This puzzle is me being a dick. The smallest number in the smallest solution has more than 80 digits. Which is pretty amazing if you think about it.

        Only non-witches get due process.

        • Cotton Mather, Salem Massachusetts, 1692
        KlausK 1 Reply Last reply
        • jon-nycJ Offline
          jon-nycJ Offline
          jon-nyc
          wrote on last edited by
          #4

          Wolfram Alpha quickly returns ‘Standard computation time exceeded’ and asks me to upgrade.

          Only non-witches get due process.

          • Cotton Mather, Salem Massachusetts, 1692
          1 Reply Last reply
          • HoraceH Offline
            HoraceH Offline
            Horace
            wrote on last edited by
            #5

            I've discovered a remarkable way to calculate this, but this forum software is inadequate to express the required mathematical notation.

            Education is extremely important.

            1 Reply Last reply
            • jon-nycJ jon-nyc

              This puzzle is me being a dick. The smallest number in the smallest solution has more than 80 digits. Which is pretty amazing if you think about it.

              KlausK Offline
              KlausK Offline
              Klaus
              wrote on last edited by Klaus
              #6

              @jon-nyc said in Puzzle Time - polynomials:

              This puzzle is me being a dick. The smallest number in the smallest solution has more than 80 digits. Which is pretty amazing if you think about it.

              But is there a way to come up with the solution analytically?

              I know that Diophantine equations are undecidable in general, and analytical solutions only exist for a few special cases.

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              • jon-nycJ Offline
                jon-nycJ Offline
                jon-nyc
                wrote on last edited by
                #7

                Yes. In fact it has to involve some clever analysis before doing automated searches. Naive messing around on a computer is not going to find an 80-digit number.

                https://drive.google.com/file/d/1NXYxl3tH7_mZMTBYL7pCeP8RY2bquVyF/view?usp=drivesdk

                The search involved elliptic curves.

                I just love how basic and innocent the problem seems. It looks like the solution should involve some one- or two-digit numbers.

                Only non-witches get due process.

                • Cotton Mather, Salem Massachusetts, 1692
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