lean_workbook_plus_57377

Proved

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

Let $x=a+b, y=a+c, z=b+c$ . Notice that $x^2+y^2+z^2=a^2+b^2+c^2+(a+b+c)^2$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_57377 : ∀ x y z a b c : ℝ, x = a + b → y = a + c → z = b + c → x^2 + y^2 + z^2 = a^2 + b^2 + c^2 + (a + b + c)^2   :=  by sorry

Source

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

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