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

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

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

directrix

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

x = - 2

Solution steps

Rewrite

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

in the standard form

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

(h, k) = (- 1, 2), 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, 2)

x-coordinate

x = - 1 - p

x = - 1 - 1

Refine

x = - 2

9 t - 2 t^{2}

x^{2} = 40 y

x^{2} - 6 x - y + 33 = 0

- 2 x^{2} + 4 x - 9

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