lean_workbook_plus_13928

Proved

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

Prove that $3(a+b+c)^{3}\geq 27(a+b+c)$ given $a,b,c\geq 1$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_13928 (a b c : ℝ) (ha : 1 ≤ a) (hb : 1 ≤ b) (hc : 1 ≤ c) : 3 * (a + b + c) ^ 3 ≥ 27 * (a + b + c)   :=  by sorry

Source