lean_workbook_plus_1215

Proved

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

Prove that $(c+d)(\frac{1}{a+d}+\frac{1}{b+c}) \ge \frac{4(c+d)}{a+b+c+d}$ given $a,b,c,d>0$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_1215 (a b c d : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) (hd : 0 < d) : (c + d) * (1 / (a + d) + 1 / (b + c)) ≥ 4 * (c + d) / (a + b + c + d)   :=  by sorry

Source

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

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