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

Question

Quizplus · Accepted Answer

The given equation is in the form $y^2 = 4ax$, where $a = -5$. The focus of a parabola in this form is $(a, 0)$, which is $(-5, 0)$. The directrix is a vertical line $x = -a$, which is $x = 5$. The axis of symmetry is the $x$-axis for parabolas in this form.

Give the Focus, Directrix, and Axis for the Parabola y2=−20xy ^ { 2 } = - 20 xy2=−20x

Give the Focus, Directrix, and Axis for the Parabola $y ^ { 2 } = - 20 x$