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Math Help - One more quadratic equation

  1. #1
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    One more quadratic equation

    Ok, I'm on my last problem and stuck again.

    16r^3-9r=0

    There's not an example in my textbook (chapter 6.6) to use as a guide (we're using "Introdutory Algebra, 8th edition by Lial, Hornsby, amd McGinnis).

    Any assistance or pointers to help would be appreciated.

    Thanks,
    Thomas
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by tbradnc View Post
    Ok, I'm on my last problem and stuck again.

    16r^3-9r=0

    There's not an example in my textbook (chapter 6.6) to use as a guide (we're using "Introdutory Algebra, 8th edition by Lial, Hornsby, amd McGinnis).

    Any assistance or pointers to help would be appreciated.

    Thanks,
    Thomas
    Take out a common factor of r to give

    r(16r^2-9) = 0

    This gives r = 0 as a factor. You can then solve the other part by using the difference of two squares:

    <br />
a^2-b^2 = (a-b)(a+b) <br />

    In your case a = 4r and b = 3
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  3. #3
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    Of course... thanks. As soon as you pointed it out I could see it.

    Hoping this will all come together for me at some point.
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