Solution
directrix 
Solution
Solution steps
Rewrite in the standard form:
Parabola is symmetric around the y-axis and so the directrix is a line parallel to the x-axis, a distance  from the center  y-coordinate 
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Frequently Asked Questions (FAQ)
What is the directrix y= 1/12 x^2 ?
The directrix y= 1/12 x^2 is y=-3