Question

The equation of directrix of the parabola $y^2=-12x$ is

• A. $x+3=0$
• B. $x=3$
• C. $y+3=0$
• D. $y-3=0$

Answer 1

Answer: (B)

Comparing the parabola
$y^2=-12x$ with $y^2=-4ax,$ we get $a=3,$
$\therefore$ Equation of directrix is $x=3$