A product of cubic and pairwise sums bounds a mixed product

Proved

WorkbookSource.base_16052

by wamlart · Sep 13, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Let $a,b,c$ be positive real numbers , prove that $(a^3+b^3+c^3)(bc+ca+ab)\ge 3abc(a^2+b^2+c^2).$

Source: InternLM Lean-Workbook, record lean_workbook_16052 (Apache-2.0). Complete source proposition preserved; proof developed independently.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.base_16052 (a b c : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) : (a^3 + b^3 + c^3) * (b * c + c * a + a * b) ≥ 3 * a * b * c * (a^2 + b^2 + c^2)  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_16052; Apache-2.0

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