Question 756283
identify the focus and directrix of the parabola given by {{{ y^2 = -4x }}}
Given parabola opens leftward:
Its basic equation: y^2=-4px
vertex: (0,0)
axis of symmetry: y=0 or x-axis
4p=4
p=1
focus: (-1,0) (p-distance to left of vertex on the axis of symmetry)
directrix: x=1  (p-distance to right of vertex on the axis of symmetry)