.9999999 Is Proven To Be Equal To 1!

Discussion in 'General Discussion' started by Aurori, Sep 12, 2007.

  1. Aurori

    Aurori Well-Known Member

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    Let me work this out in a problem to show people.

    Let's say our x = .9999 (repeating)

    1.) So that would mean that 10x = 9.999 (repeating)

    2.) 10x - x = 9 (9.999 - .9999 = 9)

    3.) so 9x = 9

    4.) Which means x = 1 once it is reduced!

    I heard about this from like all my math teachers they were freaking out. Just thought I'd share it so people in school can seem smart :).
     
  2. Amoebassassin

    Amoebassassin Well-Known Member

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    [​IMG]
     
  3. inverse

    inverse Banned from GR

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    you're ------ing kidding me...
     
  4. Genes.Buffet

    Genes.Buffet Well-Known Member

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    0.9999 x 10 is 9.999 (9.9990) not 9.9999

    And so it won't be equal to 9.

    Unless you are referring to recurring decimals.
     
  5. Aurori

    Aurori Well-Known Member

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    .9999 x 10 = 9.999

    What I mean is 9.999 repeating, sorry I didn't know how to make a repeating sign.
     
  6. inverse

    inverse Banned from GR

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    Actually, Buffet is right. This is wrong.
     
  7. Aurori

    Aurori Well-Known Member

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    I think I fixed it now, I had to let everyone know that it is .9999 REPEATING not just .9999 because then there would be zeros tagged.
     
  8. Genes.Buffet

    Genes.Buffet Well-Known Member

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    But let's say if the decimal in x = 0.9999 is a recurring one, and recurs for a infinite number of times.

    Multiplying it by ten will make the product (9.999) having it's decimal recur for (infinity - 1) times. And so, the theory will not work.

    (I might be wrong as I suck at maths.)
     
  9. -Calypso-

    -Calypso- Well-Known Member

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    Code:
    9x = 9
    You can't just change the value of the variable in mid equation.

    9x = 8.991
     
  10. Flower Of The Court

    Flower Of The Court Well-Known Member

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    Wtf. O _ O
     
  11. Aurori

    Aurori Well-Known Member

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    hmm im not quite sure what you mean but I will talk to a teacher and ask her about that

    But from how I wrote it out it seemed as if it would work!
     
  12. Aurori

    Aurori Well-Known Member

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    calypso, if you have 9.999 - .9999 you dont get 8.991 you get 9 make sure to use the 9's as a repeating number after the decimal

    at least hand written work and TI-83 shoes that
     
  13. Genes.Buffet

    Genes.Buffet Well-Known Member

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    But if you write like that in a maths test you lose marks for having the wrong nomenclature.


    And...
    You won't get 9.
     
  14. Aurori

    Aurori Well-Known Member

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    I'll take all this to the teacher and try to get bonus points for proving this theory wrong lol.

    BTW, what grade are you in buffet?
     
  15. Genes.Buffet

    Genes.Buffet Well-Known Member

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    I'm 16. (I'm Secondary 4 in Singapore, I don;t know what's the equivalent in your country.)

    Check out wikipedia (recurring decimals). It says 0.99999999999999 recurring is actually equals to one. But not in the steps you've mentioned. In fact, the steps you mentioned is even stated to be wrong.

    And good night. I gotta sleep now. School tmr. :(
     

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