Answer: B) y = (-5/56)x^2
Work Shown:
Vertex = (0,0) = (h,k)
directrix is y = 2.8
vertical distance from y = 0 to y = 2.8 is 2.8 units
2.8 = 28/10 = 14/5
p = 14/5 is the focal distance
a = -1/(4*p) = -1/(4*14/5) = -1/(56/5) = -5/56
The value of 'a' is negative because the directrix is above the focus, which means the focal point is below the vertex.
y = a(x-h)^2 + k
y = (-5/56)(x-0)^2 + 0
y = (-5/56)x^2
