lean_workbook_plus_56339

Open

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Let $a \ge 1$ and $b \ge 1$ . Show that $\log_a b = \frac{1}{\log_b a}$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_56339 (a b : ℝ) (ha : 1 ≤ a) (hb : 1 ≤ b) : Real.logb a b = 1 / Real.logb b a   :=  by sorry

Source