Answer:
y^2 = -12x
Explanation:
For a parabola whose vertex is at (0,0), its standard equation is
[tex]y^2=-4ax[/tex]where the directrix is given by x = a.
Now in our case, the vertex of our parabola is at (0,0) and the directrix is x = 3. This tells us that a = 3 and so the above equation gives
[tex]y^2=-4\cdot3x[/tex][tex]\boxed{y^2=-12x\text{.}}[/tex]which is our answer!
