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Math Help - quadratic formula

  1. #1
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    Thumbs down quadratic formula

    okay, i have this question and i have to find the roots/x-intercepts/zeros w/e of -4xsquared+5x+7 and i can't figure it out because the answer using the quadratic formula is different then the ones given (its multiple choice) can anyone help me? ... i dont know if this makes any sense though ...
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by shortd333 View Post
    okay, i have this question and i have to find the roots/x-intercepts/zeros w/e of -4xsquared+5x+7 and i can't figure it out because the answer using the quadratic formula is different then the ones given (its multiple choice) can anyone help me? ... i dont know if this makes any sense though ...
    Let's try the quadratic formula one more time:

    -4x^2 + 5x + 7 = 0

    By the quadratic formula:

    \Rightarrow x = \frac {-5 \pm \sqrt {5^2 - 4(-4)(7)}}{2(-4)}

    \Rightarrow x = \frac {-5 \pm \sqrt {137}}{-8}

    \Rightarrow x = \frac {5}{8} \pm \frac { \sqrt {137}}{8}

    what did the answers look like?
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