Question

If $x=2$ is the equation of the directrix of the parabola $y^2=-4ax$, then the focus of the parabola is

• A. $(0,1)$
• B. $(2,0)$
• C. $(-2,0)$
• D. $(0,-1)$
• E. $(-1,0)$

Answer 1

Answer: (C)

$(-2,0)$

Given equation of parabola is $y^2=-4ax$ .... (i)
Equation of directrix is $x=2$.
Compare with $x=a$, we get $a=2$
So, focus of the parabola is $(-a,0)$.
i.e, $(-2,0)$.