Why not divide numbers with null?

Discussion in 'Physics & Math' started by ProCop, Nov 21, 2002.

  1. ProCop Valued Senior Member

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    1,258
    I wonder why one cannot in maths divide numbers with null.

    Example:

    why it is not possible to state

    4/0 = 4

    (4 is divided by 0 - in other words thus 4 is NOT devided and thus remains 4.

    (the only reason which I can think of (the reason that it is not possible to divide with null) is that you can arrive at a strange result by 0/0=1 (in the sense that 0 contains 0 or the number divided by itsef is 1)

    Is there any other explanation?
     
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  3. zanket Human Valued Senior Member

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    ProCop,

    Consider that in the equation y = 4/x, as a positive x approaches zero, y approaches infinity. At 4/0 you’d be “beyond infinity” (for lack of a better term) which doesn’t make sense. If you graph out the equation y = 4/x, you’ll see what I mean; you can’t plot 4/0.
     
    Last edited: Nov 21, 2002
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  5. Prosoothus Registered Senior Member

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    1,973
    ProCop,

    Actually, any number (accept zero) divided by zero equals infinity.

    Tom
     
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  7. ProCop Valued Senior Member

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    If I understand you right, you are proposing that 0 does not really exist. (0 equals infinitely small number: number greater than 0)
     
  8. Redrover Registered Senior Member

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    234
    Look, I'll prove to you that your theory isn't true, ProCop

    Divison does two things. It tells you how many times you can fit a number of a cetain size into another number and, if you devide a number into a certain number of peices, how big those peices are.

    So you are saying 1/0 = 1
    But then 1/1 = 1
    So you could claim that
    1/1 = 1/0
    And wind up with
    1=0
     
  9. On Radioactive Waves lost in the continuum Registered Senior Member

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    985
    also, saying 0=more than zero does not make sense. i'll asume you meant "nothing" by the second zero
     
  10. allant Version 1.0 Registered Senior Member

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    88
    Take another point of view x/y = z means the answer to y * z = x.

    If y = 0 then the answer to the later is not a single answer but is any number including infinity. From this point of view, the mistake is falsely assuming that x/0 has a single answer. A natural mistake because x devided by other numbers nearly always has a single answer.
     
  11. WhiteKnight Registered Member

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    23
    Right, because x/0 has NO answers.
     
  12. James R Just this guy, you know? Staff Member

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    39,426
    <i>why it is not possible to state

    4/0 = 4</i>

    Let's multiply both sides of that equation by zero. Then we get:

    4/0 &times; 0 = 4 &times; 0

    or

    4 = 0

    That is contradictory. So, what should the answer be? i.e. what is the value of x for

    4/0 = x?

    Clearly, x cannot be any finite number. If x = infinity, then multiplying both sides by zero we get:

    4 = infinity &times; 0

    This seems ok, until you try something like 5/0, which gives:

    5 = infinity &times; 0 = 4

    or 5 = 4.

    The only solution to the problem is to say that any expression of the form

    x/0

    is <b>indeterminant</b> or <b>undefined</b>. That avoids the contradictions.
     
  13. Merlijn curious cat Registered Senior Member

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    1,014
    You beat us again, James!

    But, what would an (ordered) field look like if we were to have x/0 = 1 ?
     
  14. airdog prehensile Registered Senior Member

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    338
    The last few years, sportscasters have taken to describing a victorious team, say, in baseball, as having "doubled up" their opponent when the final score is 4-2, 6-3 etc. It's as if "doubling up" is a big deal.
    My contention is that if a team is beaten by a score of 1-0, why not say they were "infinitied up," since zero times infinity is zero! It certainly sounds more impressive to be "infinitied up" than merely being "doubled up." Actually, I say just give the damn score!
     
  15. ProCop Valued Senior Member

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    1,258
    <B>The only solution to the problem is to say that any expression of the form

    x/0

    is indeterminant or undefined. That avoids the contradictions.</b>


    OK. Really nice explanation. (But does it not mean that 0 is not fully/really a number?)
     
  16. HallsofIvy Registered Senior Member

    Messages:
    307
    "OK. Really nice explanation. (But does it not mean that 0 is not fully/really a number?)"

    I guess you would have to say what YOU mean by a number!
    The way I use the word "number" saying "we cannot divide by
    0" only means "we cannot divide by 0". It does NOT mean 0 is not a number!

    "But, what would an (ordered) field look like if we were to have x/0 = 1 ?"

    In any field (any ring, actually) 0*x= 0 so if x/0= 1 we would have to have x= 0*1= 0 for all x. That's one reason the definition of field includes "has more than one member".

    "Take another point of view x/y = z means the answer to y * z = x.

    If y = 0 then the answer to the later is not a single answer but is any number including infinity."

    No, that's not true. If x is not 0 then 0*z= x has NO answer.
    If x= 0 THEN 0*z= 0 has every number as answer. That's why
    we use the phrase "undefined" for x/0 with x not equal to 0 and
    "undetermined" for 0/0.

    By the way, infinity is NOT a standard real number. If you go around saying "x/0= infinity" without making it clear that you are just using infinity as a way of saying "does not exist" mathematicians will look at you funny.

    (Actually, if you go around saying "x/0= infinity" EVERYONE will look at you funny!)
     
  17. ProCop Valued Senior Member

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    1,258
    What I meant by being a number is having the following qualities:

    - having precise value
    - mathemathical operations (multiplying, substracting, dividing etc)are applicable to it

    Actually, when thinking about this I am inclined to place 0 as being an artificial number, (existing only for the convenience of mathematicians) because the ultimate row of numbers never begins and never ends (there exists no highest and no lowest number - no place for 0 enywhere).
     
  18. chroot Crackpot killer Registered Senior Member

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    2,350
    So the presence of an apple is natural, but the absence of an apple is artificial?

    - Warren
     
  19. thed IT Gopher Registered Senior Member

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    Sinple question, chroot is not allowed to answer,

    What is, 0/0 ?
     
  20. On Radioactive Waves lost in the continuum Registered Senior Member

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    985
    if you just press shift before you press the 5 key they already made a button for that


    see %
     
  21. kastner Purposely left blank Registered Senior Member

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    Indeterminate.<br>
    If you insist on writing down this expression and asking what it is, well, why not just use basic algebra to work it out:
    0/0 = x
    now clear the fraction by multiplying by 0
    0/0 * 0 = x* 0
    0 = x*0
    so x is...
     
  22. ProCop Valued Senior Member

    Messages:
    1,258
    RE:chroot

    <b>So the presence of an apple is natural, but the absence of an apple is artificial? </b>

    Let's have a look at the contains of my right trousers's pocket:

    The contains is
    class "natural":
    1 tissue
    3 keys

    class "artifficial":
    no money
    no gun
    no knife
    no condom( - I must remember that!!)
    no 99,99999% of the substantives of the Webster Dictionary

    How about that?
     
    Last edited: Nov 22, 2002
  23. chroot Crackpot killer Registered Senior Member

    Messages:
    2,350
    Re: RE:chroot

    Ummmm... who cares?

    - Warren
     

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