Geometry

Question Analysis  

The main focus is to determine the directrix of a vertical parabola from its equation. We need to rewrite the equation in standard form to identify the vertex and focal length.  

 

Key Concept Explanation  

Standard Form of a Vertical Parabola: The equation represents a vertical parabola with vertex . The directrix is a horizontal line given by when a > 0 (opens upward) or when a < 0 (opens downward). Here, is the distance from the vertex to the directrix.  

 

Step-by-Step Solution  

1. Rewrite the equation in standard form:  

Given , this is already in vertex form with , , and .  

2. Identify , , and :  

, so .  

Vertex:

Click "Show Answer" to reveal the answer and analysis