Since we have x=4.75 for the directrix, this tells us that the parabola's axis of symmetry runs parallel to the x-axis. This means we will use the standard form
(y-k)²=4p(x-h), where (h, k) is the vertex, (h+p, k) is the focus and x=h-p is the directrix.
Beginning with the directrix:
x=h-p=4.75 h-p=4.75
Since the vertex is at (0, 0), this means h=0 and k=0:
0-p=4.75 -p=4.75 p=-4.75
Substituting this into the standard form as well as our values for h and k we have: (y-0)²=4(-4.75)(x-0) y²=-19x
