Results 1 to 2 of 2

Math Help - Solve the equation:

  1. #1
    Newbie
    Joined
    May 2008
    Posts
    21

    Solve the equation:

    Solve the equation:
    (2/5) + 4/(10x+5) = 7/(2x+1)

    I can get it to:
    40(x^2) - 270x = -205

    The answer the book gives is:
    29/4

    Help would be appreciated on how to solve this.

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Quick's Avatar
    Joined
    May 2006
    From
    New England
    Posts
    1,024
    Quote Originally Posted by sstecken View Post
    Solve the equation:
    \frac{2}{5} + \frac{4}{10x+5} = \frac{7}{2x+1}
    let's simplify things: \frac{2}{5} + \frac{4}{5(2x+1)} = \frac{7}{2x+1}

    now let's multiply by 5(2x+1) to get: \frac{2\cdot 5\cdot (2x+1)}{5} + \frac{4 \cdot 5\cdot (2x+1)}{5(2x+1)} = \frac{7\cdot 5\cdot (2x+1)}{2x+1}

    let's cross things out: \frac{2\cdot \not 5\cdot (2x+1)}{\not 5} + \frac{4 \cdot \not 5\cdot \rlap{///////}(2x+1)}{\not 5\rlap{///////}(2x+1)} = \frac{7\cdot 5\cdot \rlap{///////}(2x+1)}{\rlap{/////}2x+1}

    so now you have: 2(2x+1) + 4 = 7\cdot5

    and work it out: 4x+2 + 4 = 35

    work it out some more: 4x+6 = 35

    subtract 6: 4x = 29

    and divide by 4: \boxed{x = \frac{29}{4}}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Solve Differential equation for the original equation
    Posted in the Differential Equations Forum
    Replies: 5
    Last Post: February 21st 2011, 01:24 PM
  2. need to solve summation equation to solve sum(x2)
    Posted in the Statistics Forum
    Replies: 2
    Last Post: July 16th 2010, 10:29 PM
  3. How to solve this equation
    Posted in the Algebra Forum
    Replies: 4
    Last Post: December 8th 2009, 05:45 AM
  4. solve this equation for x
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 26th 2009, 04:50 AM
  5. Replies: 13
    Last Post: May 19th 2008, 08:56 AM

Search Tags


/mathhelpforum @mathhelpforum