Results 1 to 8 of 8

Math Help - Simplifying Fraction

  1. #1
    Newbie
    Joined
    Mar 2011
    Posts
    23

    Simplifying Fraction

    \frac{(2ab)^-2}{2(ab)^3}

    Can this fraction be simlified ?

    I expanded it out to:

    \frac{2a^-2  +  b^-2}{2a^3  +  2b^3}

    Even in this form I can't see common factors in the numerator so does that mean this cant be simplified ?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Where did those + signs come from? The law is (ab)^n = a^nb^n

    Can you rewrite your fraction using that rule?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2011
    Posts
    23
    Quote Originally Posted by e^(i*pi) View Post
    Where did those + signs come from? The law is (ab)^n = a^nb^n

    Can you rewrite your fraction using that rule?

    Ok so

    \frac{2a^-2      b^-2}{2a^3       2b^3}

    Does this mean the a^-2 and a^3 be canceled ? Thats where im running in to trouble.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,621
    Thanks
    426
    \dfrac{(2ab)^{-2}}{2(ab)^3} = \dfrac{1}{(2ab)^2 \cdot 2(ab)^3} = (?)

    finish it
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Mar 2011
    Posts
    23
    \frac{1}{2*2*2a^2*b^2*a^3*b^3}

    \frac{1}{8a^2*b^2*a^3*b^3}

    \frac{1}{8a^2b^2*a^3*b^3}

    \frac{1}{8a^5b^5}

    Am I there ?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,089
    Thanks
    67
    "There" you are!
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Mar 2011
    Posts
    23
    In the fraction above we can move (2ab)^-2 down with the denominator and change the power, I understand that is just what you have to do but I am wondering why does this work and when can we apply this method and when not ?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,621
    Thanks
    426
    Quote Originally Posted by maca404 View Post
    In the fraction above we can move (2ab)^-2 down with the denominator and change the power, I understand that is just what you have to do but I am wondering why does this work and when can we apply this method and when not ?
    why it works ...

    you should know that \dfrac{x^a}{x^b} = x^{a-b}

    so , what do you get if a = 0 ?


    now you have the rule ...

    x^{-b} = \dfrac{1}{x^b}

    so ...

    (2ab)^{-2} = \dfrac{1}{(2ab)^2}

    ... all day long.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Simplifying fraction over fraction expression
    Posted in the Algebra Forum
    Replies: 3
    Last Post: October 17th 2010, 02:27 PM
  2. Simplifying Fraction
    Posted in the Algebra Forum
    Replies: 3
    Last Post: March 11th 2010, 11:05 PM
  3. Another fraction simplifying.
    Posted in the Algebra Forum
    Replies: 4
    Last Post: March 7th 2010, 06:51 AM
  4. Simplifying fraction
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: April 30th 2009, 05:47 AM
  5. Simplifying this fraction
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 9th 2006, 02:17 AM

Search Tags


/mathhelpforum @mathhelpforum