What is the directrix y^2-4x-4=0 ?

The directrix y^2-4x-4=0 is x=-2

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directrix y^2-4x-4=0

directrix

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

x = - 2

Solution steps

Rewrite

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

in the standard form:

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

(h, k) = (- 1, 0), p = 1

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

(- 1, 0)

x-coordinate

x = - 1 - p

x = - 1 - 1

Refine

x = - 2

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

y = - \frac{1}{12} x^{2} + x

y^{2} = 2 x

y = 6 x^{2} - 15 x

y = x^{2} - x - 20