Answer:
The directrix of parabola
is the line x = +10.
Step-by-step explanation:
The general form of parabola is given as ![y^2 = 4px](https://tex.z-dn.net/?f=y%5E2%20%3D%204px)
where the directrix is the vertical line x = - p .
If p > 0, then parabola opens to the right.
If p < 0 then parabola opens to the left.
Now here, the given equation is ![y^2 = -40x](https://tex.z-dn.net/?f=y%5E2%20%3D%20-40x)
Representing the given equation in standard form:
![y^2 = 4(-10) x](https://tex.z-dn.net/?f=y%5E2%20%3D%204%28-10%29%20x)
⇒ p = -10
So, the directrix of the parabola is x = - p = - (-10) = 10
or, x = + 10
Hence, the directrix of parabola
is the line x = +10.