lean_workbook_plus_9471

Proved

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

Prove that $4(a^2-ab+b^2) \ge (a+b)^2$ for positive reals $a$ and $b$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_9471 (a b : ℝ) (ha : 0 < a) (hb : 0 < b) : 4 * (a^2 - a * b + b^2) ≥ (a + b)^2   :=  by sorry

Source