What is the directrix 2x^2-8x+9 ?

The directrix 2x^2-8x+9 is y= 7/8

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directrix 2x^2-8x+9

directrix

y = \frac{7}{8}

Solution steps

Rewrite

y = 2 x^{2} - 8 x + 9

in the standard form

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

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

(2, 1)

y-coordinate

y = 1 - p

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

Refine

y = \frac{7}{8}