lean_workbook_plus_77780

Disproved

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

First, we prove that: $9(a+b)(b+c)(c+a) \ge 8(a+b+c)(ab+bc+ca)$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_77780 : ∀ a b c : ℝ, 9 * (a + b) * (b + c) * (c + a) ≥ 8 * (a + b + c) * (a * b + b * c + c * a)   :=  by sorry

Source