lean_workbook_plus_73686

Proved

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

Prove that: $\frac{a^4+b^4+c^4}{3}\ge\frac{(a+b+c)^4}{81}$ given $a,b,c >0$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_73686 (a b c : ℝ) (ha : a > 0) (hb : b > 0) (hc : c > 0) : (a^4 + b^4 + c^4) / 3 ≥ (a + b + c)^4 / 81   :=  by sorry

Source