Author: Margarete Bronkorsky

a = -0.4 (slider from -5 to 5, step 0.1)
b = -0.1 (slider from -5 to 5, step 0.1)
c = 4.1 (slider from -5 to 5, step 0.1)
f = Function(a * x^(2.0) + b * x + c, -5.0, 5.0)