What is the directrix y=-x^2-6x-13 ?

The directrix y=-x^2-6x-13 is y=-15/4

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directrix y=-x^2-6x-13

directrix

y = - x^{2} - 6 x - 13

y = - \frac{15}{4}

Solution steps

Rewrite

y = - x^{2} - 6 x - 13

in the standard form

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

(h, k) = (- 3, - 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

(- 3, - 4)

y-coordinate

y = - 4 - p

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

Refine

y = - \frac{15}{4}

y = + x^{2} + 5

y = + x^{2} + 6

x^{2} + 12 x + 38

x = - 3 y^{2}

- 0.2 t^{2} + 2.4 t + 98.6