What is the directrix y=-1/12 x^2 ?

The directrix y=-1/12 x^2 is y=3

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directrix y=-1/12 x^2

directrix

y = - \frac{1}{12} x^{2}

y = 3

Solution steps

Rewrite

y = - \frac{1}{12} x^{2}

in the standard form:

4 (- 3) (y - 0) = (x - 0)^{2}

(h, k) = (0, 0), p = - 3

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

(0, 0)

y-coordinate

y = 0 - p

y = 0 - (- 3)

Refine

y = 3

\frac{40 x ^{3}}{3 x}

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

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

- 2 x^{2} - 4 x + y + 70 = 0

19 - t^{2}