Modifier a, b, c

a = 1.1 (slider from -5 to 5, step 0.1)
b = -2.7 (slider from -5 to 5, step 0.1)
g = Function(-x, -10, 0)
h = Function(2 * x - 7.5, 5, 8)
c = -1.5 (slider from -5 to 5, step 0.1)
f = Function(a * x^(2) + b * x + c, 0, 5)
d: x < -12