Question:

Convert the equation to standard form by completing the square on x or y. Then find the vertex, focus?

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and directrix of the parabola. Please show work so I know you got your answer and I can learn, please.

1. x^2+6x+8y+1=0

2. y^2-2y-8x+1=0

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  1. 1.

    The standard equation of a parabola with a vertical axis is:

    (x - h)^2 = 4a(y - k) ...(1)

    The vertex is (h, k).

    The focus is (h,  k + a).

    The directrix is y = k - a.

    x^2 + 6x + 8y + 1 = 0

    x^2 + 6x = - 8y - 1

    x^2 + 6x + 3^2 = - 8y + 8

    (x + 3)^2 = - 8(y - 1)

    Comparing with (1):

    h = - 3, k = 1, a = - 2.

    The vertex is (- 3,  1).

    The focus is (- 3,  - 1).

    The directrix is y = 3.

    2.

    The standard equation of a parabola with a horizontal axis is:

    (y - k)^2 = 4a(x - h) ...(1)

    The vertex is (h, k).

    The focus is (h + a,  k).

    The directrix is x = h - a.

    y^2 - 2y - 8x + 1 = 0

    y^2 - 2y + 1 = 8x

    (y - 1)^2 = 8x

    h = 0, k = 1, a = 2.

    Vertex (0, 1).

    Focus (2, 1).

    Directrix x =  - 2.

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