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Math Help - Porabola and Vertex

  1. #1
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    Porabola and Vertex

    For f(x) = -2x^2 - 8x-2

    a. Determine whether the parabola opens up or down

    b. Find the vertex

    how can determine whether the parabola opens up or down and find the vertex? Thanks in advance.
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  2. #2
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    Re: Porabola and Vertex

    f(x) = ax^2 + bx + c

    if the leading coefficient, a , of the quadratic is positive, the parabola opens upward

    if the leading coefficient, a , of the quadratic is negative, the parabola opens downward

    the x-value of the vertex is x = \frac{-b}{2a}
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  3. #3
    Senior Member sakonpure6's Avatar
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    Re: Porabola and Vertex

    It opens down because a is negative as skeeter mentioned as as for the vertex, I also can assume you have not learned how to do vertex form? because the equation you provided does not factor.
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  4. #4
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    Re: Porabola and Vertex

    Quote Originally Posted by sakonpure6 View Post
    It opens down because a is negative as skeeter mentioned as as for the vertex, I also can assume you have not learned how to do vertex form? because the equation you provided does not factor.
    the quadratic does not need to be factorable to change it to vertex form.
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  5. #5
    Senior Member sakonpure6's Avatar
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    Re: Porabola and Vertex

    Quote Originally Posted by skeeter View Post
    the quadratic does not need to be factorable to change it to vertex form.
    I know but I think he is new to this, other wise he would have made a topic on vertex form
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