-- Mathlib/MeasureTheory/Function/Jacobian.lean
theorem addHaar_image_le_lintegral_abs_det_fderiv_aux2 (hs : MeasurableSet s) (h's : μ s ≠ ∞)
    (hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x) :
    μ (f '' s) ≤ ∫⁻ x in s, ENNReal.ofReal |(f' x).det| ∂μ

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
⊢ Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑0 * μ s))

Tactic:
apply Tendsto.mono_left _ nhdsWithin_le_nhds

Result:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
⊢ Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑0 * μ s))

Proof state:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
this :
  Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ))
ε : ℝ≥0
εpos : 0 < ε
⊢ μ (f '' s) ≤ ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s

Tactic:
exact addHaar_image_le_lintegral_abs_det_fderiv_aux1 μ hs hf' εpos

Result:
no goals

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
this :
  Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑0 * μ s))
⊢ μ (f '' s) ≤ ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ

Tactic:
simp only [add_zero, zero_mul, mul_zero, ENNReal.coe_zero] at this

Result:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
this :
  Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ))
⊢ μ (f '' s) ≤ ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
this :
  Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ))
⊢ ∀ᶠ (c : ℝ≥0) in 𝓝[>] 0, μ (f '' s) ≤ ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑c * μ s

Tactic:
filter_upwards [self_mem_nhdsWithin]

Result:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : FiniteDimensional ℝ E
s : Set E
f : E → E
f' : E → E →L[ℝ] E
inst✝² : MeasurableSpace E
inst✝¹ : BorelSpace E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
hs : MeasurableSet s
h's : μ s ≠ ⊤
hf' : ∀ x ∈ s, HasFDerivWithinAt f (f' x) s x
this :
  Tendsto (fun ε => ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑ε * μ s) (𝓝[>] 0)
    (𝓝 (∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ))
⊢ ∀ a ∈ Ioi 0, μ (f '' s) ≤ ∫⁻ (x : E) in s, ENNReal.ofReal |(f' x).det| ∂μ + 2 * ↑a * μ s