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Math Help - Quadratic Equation Solution Set

  1. #1
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    Quadratic Equation Solution Set

    I'm working on basic problems to review for a placement test into calculus. The questions are here, I don't need you to click on if your not interest, they are multiple choice. College Algebra


    Where am I going wrong here?
    x^2-2x-24=24
    x^2-2x-48=0
    x=\frac{-(-2)\pm\sqrt{(-2)^2-4(-48)(1)}}{2}=\frac{2\pm\sqrt{4+182}}{2}=\frac{2\pm\  sqrt{186}}{2}

    The solution sets (in the multiple coice) are all whole numbers. I have \pm\frac{\sqrt{186}}{2}\approx6.819

    Where am I going wrong here?
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  2. #2
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    Hi adkinsjr!

    Quote Originally Posted by adkinsjr View Post
    I'm working on basic problems to review for a placement test into calculus. The questions are here, I don't need you to click on if your not interest, they are multiple choice. College Algebra


    Where am I going wrong here?
    x^2-2x-24=24
    x^2-2x-48=0
    x=\frac{-(-2)\pm\sqrt{(-2)^2-4(-48)(1)}}{2}=\frac{2\pm\sqrt{4+182}}{2}=\frac{2\pm\  sqrt{186}}{2}

    The solution sets (in the multiple coice) are all whole numbers. I have \pm\frac{\sqrt{186}}{2}\approx6.819

    Where am I going wrong here?
    This is because 4*48 = 192 not 182

    Yours
    Rapha
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  3. #3
    MHF Contributor

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    You might also have noted that 6(8)= 48 and 8- 6= 2. That is, x^2- 2x- 48 factors as (x- 8)(x+ 6).
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