What is the directrix-((x+3)^2)/(20)+1 ?

The directrix-((x+3)^2)/(20)+1 is y=6

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directrix-((x+3)^2)/(20)+1

directrix

- \frac{( x + 3 ) ^{2}}{20} + 1

y = 6

Solution steps

Rewrite

y = - \frac{( x + 3 ) ^{2}}{20} + 1

in the standard form:

4 (- 5) (y - 1) = (x - (- 3))^{2}

(h, k) = (- 3, 1), p = - 5

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

(- 3, 1)

y-coordinate

y = 1 - p

y = 1 - (- 5)

Refine

y = 6

y = \frac{- 3 x ^{2} - 2 x + 6}{5}

X^{2}

x^{2} + 2 x + 3

y = x^{2} + 3 x - 5

y = 2 x^{2} + 5 x - 7