lean_workbook_plus_53322

Disproved

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

Is the inequality\n\n $(a+b+c-1)^2-1\geq\frac{3}{8}\cdot(a+b)(b+c)(c+a)$ \ntrue, or not?

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_53322 : ∀ a b c : ℝ, (a + b + c - 1) ^ 2 - 1 ≥ (3 / 8 : ℝ) * (a + b) * (b + c) * (c + a)   :=  by sorry

Source