by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
It's equivalent to \n\n ab+bc+ca≤3abc+2(a3+b3+c3) \n\n ⇔2(a3+b3+c3)+3abc≥(ab+bc+ca)(a+b+c)=∑ab(a+b)+3abc
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_75 {a b c : ℝ} (ha : a ≥ 0) (hb : b ≥ 0) (hc : c ≥ 0) : 2 * (a ^ 3 + b ^ 3 + c ^ 3) + 3 * a * b * c ≥ (a * b + b * c + c * a) * (a + b + c) := by sorry