lean_workbook_plus_355

Proved

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

Let $a,b,c>0$ . Show that $(a+b+c)\left( \frac{1}{a}+\frac{1}{b} + \frac{1}{c}\right) \geq 9$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_355 (a b c : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) : (a + b + c) * (1 / a + 1 / b + 1 / c) ≥ 9   :=  by sorry

Source