Question

The equation of the directrix of the parabola $y^2+4y+4x+2=0is$

• A. $x=-1$
• B. $x=1$
• C. $x=2$
• D. $x=\frac{3}{2}$

Answer 1

The correct option is D $x=\frac{3}{2}$

The given equation of parabola is,

$\Rightarrow$ $y^2+4y+4x+2=0$

$\Rightarrow$ $(y+2{)}^2+4x+2=0$

$\Rightarrow$ $(y+2{)}^2=-4(x-\frac{1}{2})$

Its directrix is $x-\frac{1}{2}=1$

$\Rightarrow$ $x=1+\frac{1}{2}$

$\Rightarrow$ $x=\frac{3}{2}$