The directrix of the parabola 2 y 2 + 25 x = 0 is _________

The directrix of the parabola $2y^2+25x=0$ is

Now,

$2y^2=-25x$

$y^2=-\frac{25}{2}x$

$y^2=-\frac{4}{4}\left(\frac{25}{2}x\right)$

$y^2=-4\left(\frac{25}{8}\right)x$

Comparing $y^2=-40x$, we get

where, $a=\frac{25}{8}$

The directrix of a parabola,

$\Rightarrow x-\frac{25}{8}=0$

$\Rightarrow 8x-25=0$.