Results 1 to 5 of 5

Math Help - avoid negative denominators

  1. #1
    Senior Member
    Joined
    Jul 2010
    Posts
    299
    Thanks
    1

    avoid negative denominators

    Hi all;
    So why avoid negative denominators?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
    From
    Mauritius
    Posts
    1,260
    Quote Originally Posted by anthonye View Post
    Hi all;
    So why avoid negative denominators?
    What do you mean? In what context? Can you post a question that you got where you have to avoid negative denominators?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Jul 2010
    Posts
    299
    Thanks
    1
    I'm just looking at some fractions and it says try to avoid negative denominators.
    Also it says if you follow convention you will never have negative denominators.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
    From
    Mauritius
    Posts
    1,260
    Hm... I'mstill unsure, but I think you mean that:

    \frac{1}{-2}

    should be avoided. Well, I think that if you follow the convention, you'll write -\frac12 instead.

    It's just a convention and there isn't a 'rule' that specifically says not to put the denominator as negative.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,550
    Thanks
    542
    Hello, anthonye!

    So why avoid negative denominators?

    I considered this question early in my teaching career.
    I found two reasons why negative denominators are undesirable.
    . . Forgive me for resorting to baby-talk.


    (1) Naming the fraction



    We want a specific share of some pie.

    The denominator indicates the size of the slices.
    . . We have divided the pie into 4 equal parts.
    . . Each part is called a "fourth".

    The numerator indicates the number of slices we want.
    . . We want 3 of those parts.
    . . Hence, we want three fourths.






    It says "Cut the pie into -4 equal parts, and take 3 slices."
    And we find that we can't do that.

    We can cut a pie into two equal parts.
    We can even cut a pie into one equal part (although it sounds silly).
    We don't know how to cut a pie into zero equal parts.
    And we certainly don't know how to cut a pie into negative-four equal parts.


    [2] Common denominator?



    The LCD seems to be -12.



    This takes more work and includes some added risk.

    . .



    FYI


    We may change any two of the signs.

    . .

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A smart way to avoid a lot of Inverse hassle?
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 29th 2010, 10:20 AM
  2. Replies: 2
    Last Post: March 26th 2009, 05:30 PM
  3. rate of train decelerating to avoid a crash
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: November 4th 2008, 06:59 PM
  4. how to avoid unwanted page-shift?
    Posted in the LaTeX Help Forum
    Replies: 1
    Last Post: May 12th 2008, 07:59 AM

Search Tags


/mathhelpforum @mathhelpforum