Find the equation of a parabola with a focus at (0,–1) and a directrix at y = 4.


y=−110(x+1)2+32
y
=
−
1
10
(
x
+
1
)
2
+
3
2

y=−110x2+32
y
=
−
1
10
x
2
+
3
2

y=−18(x+1)2+2
y
=
−
1
8
(
x
+
1
)
2
+
2

y=−18x2+32