What is the directrix (x+4)^2-1 ?

The directrix (x+4)^2-1 is y=-5/4

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directrix (x+4)^2-1

directrix

y = - \frac{5}{4}

Solution steps

Rewrite

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

in the standard form:

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

(h, k) = (- 4, - 1), 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

(- 4, - 1)

y-coordinate

y = - 1 - p

y = - 1 - \frac{1}{4}

Refine

y = - \frac{5}{4}