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Math Help - finding the x

  1. #1
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    finding the x

    hi can someone help me verifty if this is right? is there a way to put the squared sign in here?

    2xsquared - 4x - 5 = 0

    my answer was 4 √14
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  2. #2
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    Thats wrong
    Try your -b formula again

    x=2.87 or -0.87
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  3. #3
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    Quote Originally Posted by likewhoa View Post
    hi can someone help me verifty if this is right? is there a way to put the squared sign in here?

    2xsquared - 4x - 5 = 0

    my answer was 4 √14
    I've got a different solution.

    I assume that you used the quadratic formula to solve the equation(?). If so you have:

    x = \dfrac{4 \pm \sqrt{16-4 \cdot 2 \cdot (-5)}}{2 \cdot 2}

    Now simplify.
    Spoiler:
    You should now have x = 1\pm\frac12 \sqrt{14}
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  4. #4
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    Im using the quadratic formula
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  5. #5
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    so you dont combine everything inside the radical then divide?
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  6. #6
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    Quote Originally Posted by likewhoa View Post
    so you dont combine everything inside the radical then divide?
    Quote Originally Posted by earboth View Post
    you have:

    x = \dfrac{4 \pm \sqrt{16-4 \cdot 2 \cdot (-5)}}{2 \cdot 2}

    ...
    It is now plain arithmetic:

    x = \dfrac{4 \pm \sqrt{16+40}}{2 \cdot 2}

    x = \dfrac{4 \pm \sqrt{56}}{4}

    x = \dfrac{4 \pm 2 \cdot \sqrt{14}}{4}

    x = 1 \pm \frac12 \cdot \sqrt{14}
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  7. #7
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    ahhh okok thx
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  8. #8
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    Quote Originally Posted by likewhoa View Post
    hi can someone help me verifty if this is right? is there a way to put the squared sign in here?

    2xsquared - 4x - 5 = 0

    my answer was 4 √14
    Nobody mentioned how to put the squared sign in. Type:

    [tex]2x^2-4x-5=0[ /math]

    Erase the space before the /math and you get

    2x^2-4x-5=0
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