What is the directrix y=+2(x+1)^2-5 ?

The directrix y=+2(x+1)^2-5 is y=-41/8

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directrix y=+2(x+1)^2-5

directrix

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

y = - \frac{41}{8}

Solution steps

Rewrite

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

in the standard form:

4 \cdot \frac{1}{8} (y - (- 5)) = (x - (- 1))^{2}

(h, k) = (- 1, - 5), p = \frac{1}{8}

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

(- 1, - 5)

y-coordinate

y = - 5 - p

y = - 5 - \frac{1}{8}

Refine

y = - \frac{41}{8}

x - x^{2}

x^{2} + 2 x - 16 y + 65 = 0

2 x^{2} - 36 x + 324

y = (2 x - 1) (5 x - 6)

0.5 x^{2} - 3 x + 5