rw [← Real.log_rpow (by norm_num), rpow_neg (by norm_num), inv_eq_one_div (2 ^ ε), this]
𝕂 : Type u_1
inst✝ : _root_.RCLike 𝕂
ε : ℝ
εpos : 0 < ε
this : 1 - 1 / 2 ^ ε = (2 ^ ε - 1) / 2 ^ ε
⊢ 1 - 2 ^ (-ε) < ε * Real.log 2
𝕂 : Type u_1
inst✝ : _root_.RCLike 𝕂
ε : ℝ
εpos : 0 < ε
this : 1 - 1 / 2 ^ ε = (2 ^ ε - 1) / 2 ^ ε
⊢ (2 ^ ε - 1) / 2 ^ ε < (2 ^ ε).log