What is the directrix 4+2x-x^2 ?

The directrix 4+2x-x^2 is y= 21/4

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

directrix 4+2x-x^2

directrix

4 + 2 x - x^{2}

y = \frac{21}{4}

Solution steps

Rewrite

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

in the standard form

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

(h, k) = (1, 5), 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

(1, 5)

y-coordinate

y = 5 - p

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

Refine

y = \frac{21}{4}

\frac{1}{4} x^{2} + x - 8

x^{2} - 8 x - 240

- 2 x^{2} - 4 x + 34

2 x^{2} - 5 x + 5

y = \frac{x ^{2} 5 x 8}{x 3}