f(x) = x^(2)
n = 10 (slider from 1 to 100, step 1)
a = UpperSum(f, 0, 2, n)
b = LowerSum(f, 0, 2, n)
c = Integral(f, 0, 2)
tekst1: "Oversum: " + a + ""
tekst2: "Integral: " + c + ""
tekst3: "Undersum: " + b + ""