(x - h)^2 = 4p(y - k)
(-1 - 3)^2 = 4p(8 - 0.5)
(-4)^2 = 4p(7.5)
16 = 30p
p = 16/30
p = 8/15
(x - 3)^2 = 16/15(y - 0.5)
15(x^2 - 6x + 9) = 16y - 8
15x^2 - 90x + 135 = 16y - 8
16y = 15x^2 - 90x + 135 + 8
y = 15/16 x^2 - 90/16 x + 143/16
f(x) = 15/16 x^2 - 90/16x + 143/16