Ober- und Untersumme

N = 6 (slider from 1 to 50, step 1)
f(x) = (-x^(3)) + (9 * x^(2)) - (26 * x) + 26
s = Segment((-10, 0), (10, 0))
B = Point(s)
b: x(B)
A = Point(s)
a: x(A)
C = (0, -0.5)
O = UpperSum(f, a, b, N)
U = LowerSum(f, a, b, N)
T1: "a = " + (x(A))
T2: "b = " + (x(B))
T5: "Somme Majorante = " + O + ""
T4: "Somme minorante = " + U + ""
texte2: "Δx = " + ((b - a) / N) + ""
g(x) = If[1.45 ≤ x ≤ 4.6, f]