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Quadratic Equations and Inequalities question about properties of quadratic

  1. Nov 18, 2007 #1
    [SOLVED] Quadratic Equations and Inequalities question about properties of quadratic

    so here is the question

    graph the function. state the domain and range of the function.

    F(x)=-2x^2-3x+2

    i try and use the axis of symmetry (-b/2a) and then plug that into the original formula to get the vertex.
    i keep getting F(-3/2)=2

    but then when i try and plug in numbers into the formula there scattered everywhere

    F(-3/2)=2 is the vertex in the graph but i cant find the other points to show where the parabola is going

    i tried -1/2, 0, -2 and got
    (-1/2,3)
    (0,-3)
    (-2,0)

    please help me out.

    its supposed to be a upside down parabola with a domain of all real number and a range of {y|y<_ 25/8}

    <_ = less than or equal to.
     
    Last edited: Nov 18, 2007
  2. jcsd
  3. Nov 18, 2007 #2

    arildno

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    Which is correct.

    Your axis of symmetry is, however, x=-3/4.

    The maximum value of F is therefore:
    [tex]F(-\frac{3}{4})=-2(-\frac{3}{4})^{2}-3*\frac{-3}{4}+2=\frac{-18}{16}+\frac{9}{4}+2=\frac{50}{16}=\frac{25}{8}[/tex]
     
  4. Nov 18, 2007 #3
    ughhhh i put -1 for a not -2
    thanks.
     
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