A parabola can be represented by the equation y2=12⁢x. Which equation represents the directrix?

Compare y² = 12x with the standard form y² = 4px. Since 4p = 12, p = 3, so the parabola opens to the right and its directrix is x = −p = −3. Therefore, the directrix is x equal to negative 3.

AI-written and checked against the verified answer.