What is the directrix y^2-2y-4x+9=0 ?

The directrix y^2-2y-4x+9=0 is x=1

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directrix y^2-2y-4x+9=0

directrix

x = 1

Solution steps

Rewrite

y^{2} - 2 y - 4 x + 9 = 0

in the standard form

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

(h, k) = (2, 1), p = 1

Parabola is symmetric around the x-axis and so the directrix is a line parallel to the y-axis, a distance

- p

from the center

(2, 1)

x-coordinate

x = 2 - p

x = 2 - 1

Refine

x = 1