What is the directrix of the parabola given by the equation `x=y^2` ?
The for the parabola `y^2=4px` , the focus is found at `x=p` . This means for the parabola `y^2=x` , the focus is at `x=1/4` . The directrix is then the line perpendicular to the line of symmetry and equidistant from the focus and the vertex.
That means that the directrix is the line `x=-1/4`