lean_workbook_plus_15689

Disproved

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

For all real numbers $a,b,c>0$ . Prove that \n

\frac{a}{(1+a)^3}+\frac{b}{(1+b)^3}+\frac{c}{(1+c)^3}\leq \frac{3}{8}

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_15689 : ∀ a b c : ℝ, a > 0 ∧ b > 0 ∧ c > 0 → a / (1 + a) ^ 3 + b / (1 + b) ^ 3 + c / (1 + c) ^ 3 ≤ 3 / 8   :=  by sorry

Source