by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
There is a nice proof for this inequality.\n\na2+2bca2+b2+2cab2+c2+2abc2≥3(ab+bc+ca)(a+b+c)2<=>\n\na2+2bc3a2(ab+bc+ca)+b2+2ca3b2(ab+bc+ca)+c2+2ab3c2(ab+bc+ca)≥(a+b+c)2
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_14152 : ∀ a b c : ℝ, (a^2 / (a^2 + 2 * b * c) + b^2 / (b^2 + 2 * c * a) + c^2 / (c^2 + 2 * a * b) ≥ (a + b + c) ^ 2 / (3 * (a * b + b * c + a * c))) := by sorry