A fourth-power bound for pairwise squared products

Proved

WorkbookSource.base_882

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Prove that if $a,b,c\geq 0$ , then $(a+b+c)^4\geq16(a^2b^2+b^2c^2+c^2a^2)$ .

Source: InternLM Lean-Workbook, record lean_workbook_882 (Apache-2.0). Complete source proposition preserved; proof developed independently.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.base_882 (a b c : ℝ) (ha : 0 ≤ a) (hb : 0 ≤ b) (hc : 0 ≤ c) : (a + b + c) ^ 4 ≥ 16 * (a ^ 2 * b ^ 2 + b ^ 2 * c ^ 2 + c ^ 2 * a ^ 2)  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_882; Apache-2.0

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