Question 78007
vertex is mid-way between focus and directrix so focus is (0,-5)...parabola is locus of points equidistant from focus and directrix


for a point (x,y)...(y-5)^2=(x-0)^2+(y+5)^2...y^2-10y+25=x^2+y^2+10y+25...{{{y=(-x^2)/20}}}