lean_workbook_plus_81865

Disproved

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

prove that: \n $4(x^2 + y^2 + z^2)\geq x + y + z + 2(xy + yz + zx) + 3$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_81865 : ∀ x y z : ℝ, 4 * (x ^ 2 + y ^ 2 + z ^ 2) ≥ x + y + z + 2 * (x * y + y * z + z * x) + 3   :=  by sorry

Source