What is the directrix x^2+x-1 ?

The directrix x^2+x-1 is y=-3/2

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

directrix x^2+x-1

directrix

x^{2} + x - 1

y = - \frac{3}{2}

Solution steps

Rewrite

y = x^{2} + x - 1

in the standard form

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

(h, k) = (- \frac{1}{2}, - \frac{5}{4}), p = \frac{1}{4}

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{1}{2}, - \frac{5}{4})

y-coordinate

y = - \frac{5}{4} - p

y = - \frac{5}{4} - \frac{1}{4}

Refine

y = - \frac{3}{2}

y^{2} - 8 x + 2 y + 17 = 0

6 (x - 8)^{2} + 7

y^{2} + 12 x + 8 y - 44 = 0

290 (8 x + 0.5 x^{2} - 1.4)

x^{2} - x