Im Bild ist h =0.35//0.4//0.45 bei λ=5

λ = 8 (slider from 5 to 20, step 1)
f(x) = If[x ≥ 0, ℯ^(((-λ) * x))]
h = 0.25 (slider from 0 to 0.5, step 0.05)
l2 = Sequence((i * h), i, 0, 100)
l1 = Sequence(((i * h), f((i * h))), i, 0, 100)
l3 = Sequence(((i * h), (1 - (λ * h))^(i)), i, 0, 100)
I3 = NaN
l4 = Sequence(Segment[Element[l3, i], Element[l3, i + 1]], i, 1, 99)
Text1: "e^{-" + (LaTeX[λ]) + "x}"
A = (1.6609005286545817, 1.5146794158482755)
B = (2.2859817112236978, 1.5136817917554621)