have hz' : ∫ x in s, g x ∂μ = ENNReal.toReal (∫⁻ x in s, ↑‖g x‖₊ ∂μ)
f g : ℝ → ℝ
s : Set ℝ
μ : Measure ℝ
hs_ne : Set.Nonempty s
hs_meas : MeasurableSet s
hs_conn : IsPreconnected s
hs_closed : IsClosed s
hf_cont : ContinuousOn f s
hg_int : IntegrableOn g s
hg_nonneg : 0 ≤ᵐ[Measure.restrict μ s] g
h_int : IntegrableOn (fun x => f x * g x) s
⊢ ∃ c ∈ s, ∫ (x : ℝ) in s, f x * g x ∂μ = f c * ∫ (x : ℝ) in s, g x ∂μ
case hz'
f g : ℝ → ℝ
s : Set ℝ
μ : Measure ℝ
hs_ne : Set.Nonempty s
hs_meas : MeasurableSet s
hs_conn : IsPreconnected s
hs_closed : IsClosed s
hf_cont : ContinuousOn f s
hg_int : IntegrableOn g s
hg_nonneg : 0 ≤ᵐ[Measure.restrict μ s] g
h_int : IntegrableOn (fun x => f x * g x) s
⊢ ∫ (x : ℝ) in s, g x ∂μ = ENNReal.toReal (∫⁻ (x : ℝ) in s, ↑‖g x‖₊ ∂μ)

f g : ℝ → ℝ
s : Set ℝ
μ : Measure ℝ
hs_ne : Set.Nonempty s
hs_meas : MeasurableSet s
hs_conn : IsPreconnected s
hs_closed : IsClosed s
hf_cont : ContinuousOn f s
hg_int : IntegrableOn g s
hg_nonneg : 0 ≤ᵐ[Measure.restrict μ s] g
h_int : IntegrableOn (fun x => f x * g x) s
hz' : ∫ (x : ℝ) in s, g x ∂μ = ENNReal.toReal (∫⁻ (x : ℝ) in s, ↑‖g x‖₊ ∂μ)
⊢ ∃ c ∈ s, ∫ (x : ℝ) in s, f x * g x ∂μ = f c * ∫ (x : ℝ) in s, g x ∂μ