What is the directrix x^2=-8y ?

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directrix x^2=-8y

directrix

x^{2} = - 8 y

y = 2

Solution steps

Rewrite

x^{2} = - 8 y

in the standard form:

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

(h, k) = (0, 0), 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, 0)

y-coordinate

y = 0 - p

y = 0 - (- 2)

Refine

y = 2

y^{2} = 3 x

\frac{x ^{2}}{4} - y^{2} = 1

\frac{x ^{2}}{25} + \frac{y ^{2}}{4} = 1

y = - \frac{x ^{2}}{10} + \frac{9 x}{10} + \frac{11}{5}

2 y^{2} - 12 y - x + 5 = 0