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

The directrix y=-9x^2+2 is y= 73/36

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directrix y=-9x^2+2

directrix

y = \frac{73}{36}

Solution steps

Rewrite

y = - 9 x^{2} + 2

in the standard form:

4 (- \frac{1}{36}) (y - 2) = (x - 0)^{2}

(h, k) = (0, 2), p = - \frac{1}{36}

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, 2)

y-coordinate

y = 2 - p

y = 2 - (- \frac{1}{36})

Refine

y = \frac{73}{36}