What is the directrix x^2-4 ?

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directrix x^2-4

directrix

x^{2} - 4

y = - \frac{17}{4}

Solution steps

Rewrite

y = x^{2} - 4

in the standard form:

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

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

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}{4}

Refine

y = - \frac{17}{4}

y = 2 x^{2} - 13 x - 7

x = 7 y^{2}

y = 7 x^{2} - 9 x - 5

y = 3 x^{2} - 5 x 7

x^{2} - 4 x + 8