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

The directrix y=-4x^2-4 is y=-63/16

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

directrix y=-4x^2-4

directrix

y = - \frac{63}{16}

Solution steps

Rewrite

y = - 4 x^{2} - 4

in the standard form:

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

(h, k) = (0, - 4), p = - \frac{1}{16}

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 - (- \frac{1}{16})

Refine

y = - \frac{63}{16}