lean_workbook_plus_21026

Proved

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

Let $a,b,c$ be positive real numbers. Prove that \n

\frac{a^2}{(a+b)^2} + \frac{b^2}{(b+c)^2}+\frac{c}{c+a} \ge1

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_21026 (a b c : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) : (a^2 / (a + b)^2 + b^2 / (b + c)^2 + c / (c + a)) ≥ 1   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

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