Question 1028741
The FOCUS is on the other side of the vertex from the directrix.  Directrix is 2 units away from the vertex, so focus is therefore (3,0).


The basic form you chose is the right kind, which you would get or be able, if you were deriving the equation for your parabola using the definition of Parabola and Distance Formula.


{{{(y-0)^2=-4p(x-5)}}}, and you are supposed to understand {{{-4p=-4*2}}}, meaning {{{p=2}}}.  Combining those,  {{{y^2=-8(x-5)}}}.  Continuing toward standard form,
{{{(1/8)y^2=-8x+40}}}
{{{-(1/8)y^2=x-5}}}
{{{highlight(x=-(1/8)y^2+5)}}}