What is the directrix x=-4y^2 ?

The directrix x=-4y^2 is x= 1/16

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directrix x=-4y^2

directrix

x = - 4 y^{2}

x = \frac{1}{16}

Solution steps

Rewrite

x = - 4 y^{2}

in the standard form:

4 (- \frac{1}{16}) (x - 0) = (y - 0)^{2}

(h, k) = (0, 0), p = - \frac{1}{16}

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

- p

from the center

(0, 0)

x-coordinate

x = 0 - p

x = 0 - (- \frac{1}{16})

Refine

x = \frac{1}{16}

y^{2} - 10 x + 4 y - 16 = 0

- 4 x^{2} + 6 x - 1

y = - 2 x^{2} + 8 x

y = - 4 x^{2} - 4

(x - 4)^{2} = - 8 (y + 3)