What is the directrix-x^2+8x-7 ?

The directrix-x^2+8x-7 is y= 37/4

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directrix-x^2+8x-7

directrix

- x^{2} + 8 x - 7

y = \frac{37}{4}

Solution steps

Rewrite

y = - x^{2} + 8 x - 7

in the standard form

4 (- \frac{1}{4}) (y - 9) = (x - 4)^{2}

(h, k) = (4, 9), 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, 9)

y-coordinate

y = 9 - p

y = 9 - (- \frac{1}{4})

Refine

y = \frac{37}{4}

y = x^{2} - 5 x + 4

y = x^{2} - x - 6

+ x^{2} + 12

y = 5 x^{2} + 210 x - 34775

y^{2} - 6 y - 4 x + 5 = 0