English
For any c in R, the function exp(x) restricted to Iic(c) is integrable on that interval.
Русский
Для любого c ∈ ℝ функция exp(x) на отрезке Iic(c) интегрируема.
LaTeX
$$$$ \\text{IntegrableOn}(e^{x}, [ -\\infty, c ])$$$$
Lean4
theorem integrableOn_exp_Iic (c : ℝ) : IntegrableOn exp (Iic c) :=
by
refine
integrableOn_Iic_of_intervalIntegral_norm_bounded (exp c) c (fun y => intervalIntegrable_exp.1) tendsto_id
(eventually_of_mem (Iic_mem_atBot 0) fun y _ => ?_)
simp_rw [norm_of_nonneg (exp_pos _).le, integral_exp, sub_le_self_iff]
exact (exp_pos _).le