by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
Applying AM-GM, we get \n 4(b2+bc+c2)(ab+bc+ca)≤(ab+bc+ca+b2+bc+c2)2=(b+c)2(a+b+c)2
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_74766 (a b c : ℝ) :
4 * (b^2 + b * c + c^2) * (a * b + b * c + c * a) ≤ (a * b + b * c + c * a + b^2 + b * c + c^2)^2 := by sorry