What is the directrix x^2=-28y ?

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directrix x^2=-28y

directrix

x^{2} = - 28 y

y = 7

Solution steps

Rewrite

x^{2} = - 28 y

in the standard form:

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

(h, k) = (0, 0), p = - 7

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 - (- 7)

Refine

y = 7

f (x) = - x^{2} + 4 x - 3

3 y + 4 x = - 2 x^{2} - 14

x^{2} = 20 y

\frac{x ^{2}}{169} + \frac{y ^{2}}{25} = 1

\frac{y ^{2}}{9} - \frac{x ^{2}}{4} = 1