Given the equation of an parabola, find the vertex, focus and directrix

The video tutorial explains how to solve for P in a mathematical equation by eliminating coefficients of the squared term. It then guides through identifying the vertex and determining the graph's orientation, whether it opens to the right or left. The tutorial further explains how to find the focus and directrix, emphasizing the importance of plotting for better visualization.

Explain how the focus is determined in relation to the vertex.

What is the equation of the directrix as derived in the discussion?