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Math Help - parabola homework help plz

  1. #1
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    parabola homework help plz

    parabola equation y=3x^2+4.5

    Give the coordinates of the vertex of the parabola.
    What ia the axis of symmetryof the parabola?

    what are the y intercepts of the parabola?

    Approxemetly what are the x intercepts of the parabola?

    Question 2

    parabola equation y=-1/3(x+2)^2-7/6

    give the coordinates of the vertex of the parabola

    what is he axies of symmetry of the parabolagiven by the graph.

    what are the y intercepts of the parabola

    approximetly what r the x intercepts of the parabola
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by gumi View Post
    parabola equation y=3x^2+4.5

    Give the coordinates of the vertex of the parabola.
    there are two ways to go about this:

    (1) use completing the square to get the quadratic in the form y = a(x - h)^2 + k

    in which case, the vertex is (h,k)


    (2) use the vertex formula.

    for the vertex of the quadratic f(x) = ax^2 + bx + c, we have:

    x = \frac {-b}{2a}

    so the vertex is \left( \frac {-b}{2a}, f \left( \frac {-b}{2a} \right) \right)


    What ia the axis of symmetry of the parabola?
    we have an upward opening parabola here. the axis of symmetry is just the vertical line passing through the vertex.

    if you used method (1) above, the axis of symmetry is x = h

    if you used method (2), the axis of symmetry is x = \frac {-b}{2a}


    what are the y intercepts of the parabola?
    set x = 0 and solve for y

    Approxemetly what are the x intercepts of the parabola?
    set y = 0 and solve for x



    the same methods can be used for the second question
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  3. #3
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    thanks
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