case hz
f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : ↑abs z < R
⊢ z ∈ ball 0 R

f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : z ∈ ball 0 R
⊢ ↑abs (f z) ≤ ↑abs z
f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : ↑abs z < R
⊢ ↑abs (f z) ≤ ↑abs z
replace hz : z ∈ ball (0 : ℂ) R
f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : z ∈ ball 0 R
⊢ ↑abs (f z) ≤ ↑abs z
case hz
f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : ↑abs z < R
⊢ z ∈ ball 0 R

f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : z ∈ ball 0 R
⊢ ↑abs (f z) ≤ ↑abs z
exact mem_ball_zero_iff.2 hz
no goals
f : ℂ → ℂ
c z : ℂ
R R₁ R₂ : ℝ
hd : DifferentiableOn ℂ f (ball 0 R)
h_maps : MapsTo f (ball 0 R) (ball 0 R)
h₀ : f 0 = 0
hz : z ∈ ball 0 R
⊢ ↑abs (f z) ≤ ↑abs z
simpa only [dist_zero_right] using dist_le_dist_of_mapsTo_ball_self hd h_maps h₀ hz