f(x) = 1 / x
g(x) = 1 / (x + 1)
A: (2, f(2))
B: (2, g(2))
C: (3, f(3))
D: (3, g(3))
E: (4, f(4))
F = Intersect(g, a, (1, 0.55))
b = Segment(F, A)
c = Segment(B, A)
d = Segment(B, C)
e = Segment(C, D)
h = Segment(D, E)
i = UpperSum(g, 1, 10, 9)
f_1(x) = 1 / x - 1 / (x + 1)
j = LowerSum(f_1, 0, 10, 10)