lean_workbook_plus_73658

Proved

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

Let $a,b,c$ be real numbers . Prove that $3|a|+|a+3b|+|5b+c|+5|c|\geq \frac{28}{19}(|a+b+4c|)$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_73658 (a b c : ℝ) : 3 * |a| + |a + 3 * b| + |5 * b + c| + 5 * |c| ≥ (28 / 19) * |a + b + 4 * c|   :=  by sorry

Source