lean_workbook_plus_17499

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Prove: ${\left( {\sum {a^2}} \right)^2} \ge 3\sum {{a^2}{b^2}}$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_17499 (a b c : ℝ) : (a ^ 2 + b ^ 2 + c ^ 2) ^ 2 ≥ 3 * (a ^ 2 * b ^ 2 + b ^ 2 * c ^ 2 + c ^ 2 * a ^ 2)   :=  by sorry

Source