What is the directrix-3x^2+17x-20 ?

The directrix-3x^2+17x-20 is y= 25/6

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directrix-3x^2+17x-20

directrix

- 3 x^{2} + 17 x - 20

y = \frac{25}{6}

Solution steps

Rewrite

y = - 3 x^{2} + 17 x - 20

in the standard form

4 (- \frac{1}{12}) (y - \frac{49}{12}) = (x - \frac{17}{6})^{2}

(h, k) = (\frac{17}{6}, \frac{49}{12}), 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

(\frac{17}{6}, \frac{49}{12})

y-coordinate

y = \frac{49}{12} - p

y = \frac{49}{12} - (- \frac{1}{12})

Refine

y = \frac{25}{6}

y + 1 = 5 (x - 2)^{2}

y = 4 x^{2} + 5

(x + 4)^{2} - 3

x^{2} + 12 x + 6 y + 10 = 0

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