What is the directrix x^2=8(y+4) ?

The directrix x^2=8(y+4) is y=-6

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directrix x^2=8(y+4)

directrix

x^{2} = 8 (y + 4)

y = - 6

Solution steps

Rewrite

x^{2} = 8 (y + 4)

in the standard form:

4 \cdot 2 (y - (- 4)) = (x - 0)^{2}

(h, k) = (0, - 4), p = 2

Parabola is symmetric around the y-axis and so the directrix is a line parallel to the x-axis, a distance

- p

from the center

(0, - 4)

y-coordinate

y = - 4 - p

y = - 4 - 2

Refine

y = - 6

y = 2 x (x - 9) - (x - 9)

y = 2 x^{2} - 10 x + 12

- x^{2} + 14 x - 45

y = x^{2} + 5 x + 6

y^{2} = 6 x