lean_workbook_plus_13424

Proved

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

If a,b,c are non-negative real numbers, then $a^2 + b^2 + c^2 - ab - bc - ca \geq 0$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_13424 (a b c: ℝ) : a^2 + b^2 + c^2 - (a * b + b * c + c * a) ≥ 0   :=  by sorry

Source