What is the directrix 4-7x^2 ?

The directrix 4-7x^2 is y= 113/28

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directrix 4-7x^2

directrix

4 - 7 x^{2}

y = \frac{113}{28}

Solution steps

Rewrite

y = 4 - 7 x^{2}

in the standard form:

4 (- \frac{1}{28}) (y - 4) = (x - 0)^{2}

(h, k) = (0, 4), p = - \frac{1}{28}

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, 4)

y-coordinate

y = 4 - p

y = 4 - (- \frac{1}{28})

Refine

y = \frac{113}{28}

3 x^{2} - x - 4

y = x^{2} - 10 x - 4

y = - 3 x^{2}

y = 3.1 + 6.6 x - 2.3 x^{2}

y = 3 x^{2} 4