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Solving Quadratic Equation Using Box Factoring

  1. Jul 29, 2011 #1
    1. The problem statement, all variables and given/known data


    f(x)=6x^2+9x-6

    Where does this function intersect the x-axis (i.e. what are the roots or zeroes of f(x))?

    Solve by factoring using the Box Method. When I use the method that is shown on this website http://www.purplemath.com/modules/factquad2.htm for this particular problem I end up with this as my factored down version of the equation.
    (6x-3)(3x+6)
    But that is wrong because I would end up with 18x^2 as my leading term instead of the 6x^2 (which is in the desired equation) when I FOIL them out.

    My question is that does using the method on that website to factor down a quadratic work for this equation? If so, could someone tell me what I'm doing wrong.

    Thanks :)

    2. Relevant equations



    3. The attempt at a solution
    [PLAIN]http://5img.com/img836/4599/69quadproblem.jpg [Broken]
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Jul 29, 2011 #2

    I like Serena

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    Homework Helper

    Welcome to PF, nordqvist11! :smile:

    Your equation looks like the last example on the page you mentioned.
    It says there that you should take out the common factor first...
     
  4. Jul 29, 2011 #3
    You're right it does :). Thanks a lot, I got a real headache because of that.
     
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