What is the directrix y=x^2-9x+20 ?

The directrix y=x^2-9x+20 is y=-1/2

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directrix y=x^2-9x+20

directrix

y = x^{2} - 9 x + 20

y = - \frac{1}{2}

Solution steps

Rewrite

y = x^{2} - 9 x + 20

in the standard form

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

(h, k) = (\frac{9}{2}, - \frac{1}{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

(\frac{9}{2}, - \frac{1}{4})

y-coordinate

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

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

Refine

y = - \frac{1}{2}

x^{2} - 6 x + 5 y = 34

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

y = \frac{1}{3} x^{2} + 6 x + 10

F = \frac{m v ^{2}}{r}

- x^{2} + 6 x + 1