Jika fungsi kuadrat y=f(x) mencapai minimum di titik (1,-4) dan f(4)=5, maka f(x)=…

Minimum di titik (1, -4)
p = 1
q = -4

f(4) = 5
x = 4
y = 5

y = a(x – p)² + q
5 = a(4 – 1)² – 4
5 + 4 = a(3)²
9 = 9a
a = 1

y = a(x -1)² – 4
y = 1(x² – 2x + 1) – 4
y = x² – 2x – 3

f(x) = x² – 2x – 3