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Quadratic function - x-intercepts?

  1. Apr 21, 2004 #1
    f(x) = -2x^2 + 12x + 12

    I was able to express it in standard form and find the maximum value, but I can't seem to get the x-intercepts

    I got -2x^2 + 12x + 12 = 0
    -2 (x^2 - 6x + 6) = 0

    does that mean I need to use the quadratic formula or did I do something wrong?
     
  2. jcsd
  3. Apr 21, 2004 #2

    Zurtex

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    There is a Homework help zone. But you have:

    -2 (x^2 - 6x + 6) = 0

    If a product equals 0 at least one of the bits of the product must equal 0. So either:

    -2 = 0

    or:

    x^2 - 6x + 6 = 0

    I think we can safely assume that -2 does not equal 0. So now you can solve:

    x^2 - 6x + 6 = 0

    By using the quadratic equation or completing the square (although it would have been just as easy to use the quadratic equation on -2x^2 + 12x + 12) I'm fairly sure this does not factorise.
     
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