lean_workbook_plus_22387

Proved

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

prove that $\frac {3(ab + bc + ca)}{(a + b + c)^2}\leq 1$ where $a, b, c$ are positive numbers.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_22387 (a b c : ℝ) : (3 * (a * b + b * c + c * a)) / (a + b + c) ^ 2 ≤ 1   :=  by sorry

Source