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Why is a x b written as ab?

  1. Jul 27, 2004 #1
    Why is a x b written as ab? Is it just for the purpose of abbreviation so you dont have to write as much or because the multiplication sign could be mistaken for a letter x?
  2. jcsd
  3. Jul 27, 2004 #2


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    The 'x' holds a special meaning for multiplication of vectors: The Cross Product

    It's also possible to mistake it for the letter x.
  4. Jul 27, 2004 #3
    People are lazy, and it's "a lot" easier to write [tex]ab[/tex] instead of [tex]a \cdot b[/tex] or [tex]a \times b[/tex].
  5. Jul 27, 2004 #4
    To go along with enigma wrote, when I saw your question in the list, I assumed that you were talking about vectors and the cross product!! :smile:
  6. Jul 27, 2004 #5
    As my genious highschool calc teacher always used to say, "Good mathematicians are notoriously lazy." And its true. Its just written that way out of convention to save the effort of having to write the x. I don't think that x is "reserved" for the cross product. I mean lots of symbols have 2 meanings you can tell which is referred to by context. For example l l is used to mean absolute value in some cases and it is also used to denote the order of a group.
  7. Jul 27, 2004 #6


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    I don't think good mathematicians are lazy. Anyone who has ever gotten anywhere must have worked hard for it and I`m sure that's true for all mathematicians in history. It's just that mathematicians work hard to make things as easy as possible so they can be lazy :P
  8. Jul 27, 2004 #7


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    And [itex]\cdot[/itex] is supposed to be the decimal place and [itex].[/itex] is supposed to be the multiplication symbol, but people just forget out of ease of writting.
  9. Jul 27, 2004 #8
    This page talks about the origins of different symbols for math operations:


    From the first section on multiplication:

  10. Jul 27, 2004 #9
    It's an intuitive notation. 3b seems to imply you have three b's. ab seems to imply you have a b's.

    No doubt, but it gets an easy laugh out of a class full of students who resent math.
  11. Jul 29, 2004 #10
    hehehe..in my opinion , as the process on solving the mathematic problem may take long solution and applying many formula . To avoid confusing and easy to solve , so the mathematicians introduce those symbol to make the job easy.
    e.g :
    pai = 3.142.....
    a x b = a.b = ab ( multiplied )
    a -- b = a/b ( divided )

    p/s : sorry i not really know on using computer and don't know where to find all those mathematics symbol...sorry.. :rofl:
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