lean_workbook_plus_76601

Proved

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

Prove that $(a+3b)^2 + (3b+2c)^2 \geq \frac{(a+6b+2c)^2}{2}$ using Titu's lemma.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_76601 : ∀ a b c : ℝ, (a + 3 * b) ^ 2 + (3 * b + 2 * c) ^ 2 ≥ (a + 6 * b + 2 * c) ^ 2 / 2   :=  by sorry

Source