What is the directrix y=3x^2-5 ?

The directrix y=3x^2-5 is y=-61/12

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directrix y=3x^2-5

directrix

y = 3 x^{2} - 5

y = - \frac{61}{12}

Solution steps

Rewrite

y = 3 x^{2} - 5

in the standard form:

4 \cdot \frac{1}{12} (y - (- 5)) = (x - 0)^{2}

(h, k) = (0, - 5), p = \frac{1}{12}

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, - 5)

y-coordinate

y = - 5 - p

y = - 5 - \frac{1}{12}

Refine

y = - \frac{61}{12}

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

y^{2} - 6 y - 8 x + 17 = 0

y^{2} + 6 y + 2 x + 1 = 0

y = x^{2} - 7

2 x - 5 x^{2}