Find the focus and directrix of the parabola.
-$$y ^ { 2 } = - 20 x$$
A) (-5, 0); x = 5
B) (-5, 0); y = 5
C) (5, 0); x = -5
D) (0, -5); y = 5

Question

Quizplus · Accepted Answer

The given equation is $y^2 = -20x$, which is a parabola that opens to the left. The general form of a parabola opening left or right is $y^2 = 4ax$. Comparing, we find $4a = -20$, so $a = -5$. The focus of such a parabola is $(-a, 0)$ or $(-5, 0)$, and the directrix is $x = a$ or $x = 5$.

Find the Focus and Directrix of the Parabola y2=−20xy ^ { 2 } = - 20 xy2=−20x

Find the Focus and Directrix of the Parabola $y ^ { 2 } = - 20 x$