Results 1 to 6 of 6
Like Tree4Thanks
  • 1 Post By adkinsjr
  • 2 Post By Soroban
  • 1 Post By HallsofIvy

Math Help - rational expressions #2

  1. #1
    Member
    Joined
    Feb 2013
    From
    Canada
    Posts
    131

    Post rational expressions #2



    i cannot finish 1 c) and d)... that is how far i got.

    i am having some problems with turning trinomials with no common factors into binomials

    thank you
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2009
    From
    United States
    Posts
    676
    Thanks
    19

    Re: rational expressions #2

    In (c) just find the roots of the quadratic equation you're trying to factor, which are 4 and \frac{5}{2}. So one factor would have to be (x-4) and the other would have to be 2z-5. Try something similar to the other problem you're working on.
    Thanks from Mathnood768
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,710
    Thanks
    630

    Re: rational expressions #2

    Hello, Mathnood768!

    You need more Factoring practice.


    (c)\;\frac{4z^2-25}{2z^2 - 13z + 20} \times \frac{z-4}{4z+10}

    Factor and reduce: . \frac{({\color{blue}\rlap{//////}}2z+5)({\color{red}\rlap{//////}}2z-5)}{({\color{red}\rlap{//////}}2z-5)({\color{green}\rlap{/////}}z-4)} \times \frac{{\color{green}\rlap{/////}}z-4}{2({\color{blue}\rlap{//////}}2z+5)} \;\;=\;\;\frac{1}{2}




    (d)\;\frac{8y^2-2y-3}{y^2-1} \div \frac{2y^2-3y-2}{2y-2} \div \frac{3-4y}{y+1}

    \frac{8y^2-2y-3}{y^2-1} \times \frac{2y-2}{2y^2-3y-2} \times \frac{y+1}{-(4y-3)}

    . . =\;\frac{({\color{blue}\rlap{//////}}2y+1)({\color{red}\rlap{//////}}4y-3)}{(\rlap{/////}y+1)({\color{green}\rlap{/////}}y-1)} \times \frac{2({\color{green}\rlap{/////}}y-1)}{(y-2)({\color{blue}\rlap{//////}}2y+1)} \times -\frac{\rlap{/////}y+1}{{\color{red}\rlap{//////}}4y-3}

    . . =\;-\frac{2}{y-2} \;=\;\frac{2}{2-y}
    Thanks from Mathnood768 and topsquark
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Feb 2013
    From
    Canada
    Posts
    131

    Re: rational expressions #2

    thank you!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Feb 2013
    From
    Canada
    Posts
    131

    Re: rational expressions #2

    why is it not 2/y - 2 though? why do you say its negative?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,569
    Thanks
    1410

    Re: rational expressions #2

    The minus comes from the 3- 4y in the original problem. In order to be able to cancel with the 4y- 3 which is a factor 8y^2- 2y- 3= (2y+ 1)(4y- 3), Soroban factored out a "-1" writing it as -(4y- 3).
    Thanks from Mathnood768
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. rational expressions help.
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 13th 2012, 12:35 PM
  2. Rational expressions?
    Posted in the Algebra Forum
    Replies: 5
    Last Post: March 4th 2011, 06:29 PM
  3. Rational Expressions and Radical Expressions
    Posted in the Algebra Forum
    Replies: 16
    Last Post: July 9th 2009, 09:29 PM
  4. Rational Expressions
    Posted in the Algebra Forum
    Replies: 3
    Last Post: March 19th 2007, 04:09 PM
  5. Rational expressions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 15th 2006, 04:12 PM

Search Tags


/mathhelpforum @mathhelpforum