no goals
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
R R₁ R₂ : ℝ
f : ℂ → E
c z z₀ : ℂ
hd : DifferentiableOn ℂ f (ball c R₁)
h_maps : MapsTo f (ball c R₁) (ball (f c) R₂)
h₀ : 0 < R₁
⊢ ‖deriv f c‖ ≤ R₂ / R₁
simpa only [dslope_same] using norm_dslope_le_div_of_mapsTo_ball hd h_maps (mem_ball_self h₀)