What is the directrix x^2+6x-8 ?

The directrix x^2+6x-8 is y=-69/4

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directrix x^2+6x-8

directrix

x^{2} + 6 x - 8

y = - \frac{69}{4}

Solution steps

Rewrite

y = x^{2} + 6 x - 8

in the standard form

4 \cdot \frac{1}{4} (y - (- 17)) = (x - (- 3))^{2}

(h, k) = (- 3, - 17), 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, - 17)

y-coordinate

y = - 17 - p

y = - 17 - \frac{1}{4}

Refine

y = - \frac{69}{4}

y = x^{2} + 4 x - 3

y = 18 x^{2} - 6 x + 4

7 x^{2} - 7 x

y = + x^{2} + 8 x + 6

y = (x + 3) (x - 1)