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Math Help - Odd factoring in textbook

  1. #1
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    Odd factoring in textbook

    Though this is for a calculus problem, I've gotten all the calc worked out. I just don't understand how the book came to this conclusion after factoring!

    3x^2 - 12x + 11 = 0
    The answer the book comes to is

    (6 + sqrt(3)) / 3
    (6 - sqrt(3)) / 3

    The way I did it in the first place was:
    3x^2 - 12x = -11
    3x(x - 4) = -11
    Therefore
    x = -11 / 3
    x = -7

    What were they doing in my textbook? Unfortunately they give no clues and I've been staring at it for 15 minutes now.
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  2. #2
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    Quote Originally Posted by hibernaldream View Post
    Though this is for a calculus problem, I've gotten all the calc worked out. I just don't understand how the book came to this conclusion after factoring!

    3x^2 - 12x + 11 = 0
    The answer the book comes to is

    (6 + sqrt(3)) / 3
    (6 - sqrt(3)) / 3

    The way I did it in the first place was: this is not the correct method to solve a quadratic equation.
    3x^2 - 12x = -11
    3x(x - 4) = -11
    Therefore
    x = -11 / 3
    x = -7


    What were they doing in my textbook?
    they used the quadratic formula.
    ...
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  3. #3
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    Ah. I forgot that existed. I took algebra five years ago, hence the confusion. Thanks.
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