对称轴 x=-\frac{b}{2a}

a = 1 (slider from 1 to 5)
b = 3.8 (slider from -10 to 10)
c = 0 (slider from -5 to 5)
f: y = (a * x^(2)) + (b * x) + c
g: y = x^(2)
A = Extremum(f)