Question 35466
{{{y^2 = -16x }}} is a parabola that opens to the left.  The vertex of course is the origin (0,0).  The focus and directix are at a distance of p from the vertex, where 4p = 16, so p=4.  The focus is within the arc of the parabola, so it will be to the left of the origin at (-4,0) and the directrix will be to the right of the vertex.  The directrix will be the vertical line x = 4.  The graph will be

{{{ graph (300, 300, -10, 10, -10, 10, sqrt(-16x), -sqrt(-16x))}}}


R^2 at SCC