The parabola whose equation is y 2 = 12x has directrix of: x = 3 x = -3 y = 3 y = -3

The parabola whose equation is y 2 = 12x has directrix of:
x = 3
x = -3
y = 3
y = -3

The directrix is:
 x=-3

One way of solving is to assign values for x and y:
x       y
0      0
1      3.46
1     -3.46
2      4.9
2     -4.9

When graphed, the solution is:
Direction: Opens RightVertex: (0,0)(0,0)Focus: (3,0)(3,0)Axis of Symmetry: y=0Directrix: x=−3