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Math Help - Factoring a quadratic equation

  1. #1
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    Factoring a quadratic equation

    I'm stuck on this one....

    6r^2-r-2=0

    Any assistance appreciated.

    Thanks
    Thomas
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by tbradnc View Post
    I'm stuck on this one....

    6r^2-r-2=0

    Any assistance appreciated.

    Thanks
    Thomas
    Hi tbradnc,

    Here's a technique you can use.

    Multiply the leading coefficient (6) by the constant (-2).

    This gives you -12.

    The coefficient of the middle term is -1.

    You need a pair of numbers whose product is -12 and whose sum is -1.

    After thinking a bit on this, you should come up with the only combination that works, namely -4 and 3.

    Now restate your quadratic replacing the middle coefficient with these two.

    6r^2{\color{red}-4r +3r}-2

    Now group the first two terms, and then the last two terms.

    (6r^2-4r)+(3r-2)

    Factor each group.

    2r(3r-2)+1(3r-2)

    (3r-2) is a common factor, so

    (3r-2)(2r+1)

    All done.
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  3. #3
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    Thank you so much....I'm so glad I found this site. ;-)

    I'm an older adult going back to school and it's been 30 years since I've played with algebra. I leave every class barely understanding what we're doing and I have to drill, drill, drill to get the hang of it.
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