Question

Equation of directrix for the parabola $x^2=-24y$ is

• A. $y=-3$
• B. $y=6$
• C. $y=-6$
• D. $y=3$

Answer 1

The correct option is B $y=6$

Equation of the directrix of parabola of form $x^2=4ay$ is $y=-a$

Here equation of parabola is $x^2=-24y$

$\Rightarrow 4a=-24$

$\Rightarrow a=-6$

So the equation of directrix is

$y=-(-6)$

$y=6$

So option $B$ is correct.