a = 2 (slider from -15 to 15, step 0.5)
b = 6 (slider from -15 to 15, step 0.5)
c = -11 (slider from -15 to 15, step 0.5)
f(x) = (a * x^(2)) + (b * x) + c
X1, X2 = Intersect(f, xAxis)
p: b / a
q: c / a