a = -2 (slider from -10 to 10, step 1)
b = -2 (slider from -10 to 10, step 1)
c = 6 (slider from -10 to 10, step 1)
d = 3 (slider from -10 to 10, step 1)
f(x) = a x^(3) + b x^(2) + c x + d