Question 933222
What is the directrix of the parabola represented by 
{{{ (y+4)^2=8(x-5) }}}
This is an equation of a parabola that opens rightward
Its basic form of equation: (y-k)^2=4p(x-h), (h,k)=coordinates of the vertex
For given equation:
vertex:(5,-4)
axis of symmetry: y=-4
4p=8
p=4
directrix: x=1 (p-distance left of vertex on the axis of symmetry)