What is the directrix (x+1)^2=-12(y-6) ?

The directrix (x+1)^2=-12(y-6) is y=9

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directrix (x+1)^2=-12(y-6)

directrix

(x + 1)^{2} = - 12 (y - 6)

y = 9

Solution steps

Rewrite

(x + 1)^{2} = - 12 (y - 6)

in the standard form:

4 (- 3) (y - 6) = (x - (- 1))^{2}

(h, k) = (- 1, 6), p = - 3

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

(- 1, 6)

y-coordinate

y = 6 - p

y = 6 - (- 3)

Refine

y = 9

4 x^{2} - 12 x - 2

3 x^{2} + 4 x - 3

y = 600 - 10 x + 0.25 x^{2}

11 x^{2} + 13

- 2 (x + 3) = (y - 1)^{2}