Question

The equation of the directrix of the parabola $x^2+8y-2x=7$ is

• A. $y=3$
• B. $y=-3$
• C. $y=2$
• D. $y=0$

Answer 1

Answer: (A)

$y=3$

$x^2+8y-2x=7\Rightarrow x^2-2x+1=8-8y$
$\Rightarrow (x-1{)}^2=8(1-y)$
$\Rightarrow (x-1{)}^2=-4\times (2\left)\right(y-1\left)\right[\because x^2=-4ay]$
Hence, the equation of the directrix of the parabola will be $Y=y-1=a\Rightarrow y-1=2$ i.e., $y=3$