Simple Quadratic Formula Q.?

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  1. 24hoursmiles's Avatar
    1 16-06-2012  18:30
    • Respected Member
    • Posts: 216
    Simple Quadratic Formula Q.?
    Hello
    So here's a question, from a paper (unit 3 edexcel)

    Solve 5x2 – 3x – 7 = 0

    Give your solutions correct to 3 significant figures.

    The answers from the mark scheme are: 1.52 & -0.921

    however when I use the quadratic formula, I cant seem to get this answer!
    Please help!
  2. Damask-'s Avatar
    2 16-06-2012  21:44
    • Benevolent Member
    • Location: Surrey
    • Posts: 896
    Re: Simple Quadratic Formula Q.?
    A is 5, B is -3, C is -7. Plug those into the formula.

    \begin{array}{*{20}c} {x = \frac{{ - b \pm \sqrt {b^2 - 4ac} }}{{2a}}}
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