lean_workbook_plus_35007

Proved

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

Further simplification gives $2(ab+bc+ca)+a^2+b^2+c^2 \ge 0$ which is equivalent to $(a+b+c)^2 \ge 0$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_35007 (a b c : ℝ) : 2 * (a * b + b * c + c * a) + a ^ 2 + b ^ 2 + c ^ 2 ≥ 0   :=  by sorry

Source