p = -0.5 (slider from -5 to 5, step 0.1)
q = 2 (slider from -5 to 5, step 0.1)
r = 2.3 (slider from -5 to 5, step 0.1)
f(x) = (p * (x - q)^(2)) + r
R: (0, r)
Q: (q, 0)
A = Extremum(f)
g = Line(A, Q)
h = Line(A, R)