by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
Let x,y,z>0 . Prove that the following inequality holds: xy+yz+zxx2+y2+z2≥1+(zx+y+yz+x+xy+z)−4(y+zx+z+xy+x+yz).
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_54144 : ∀ x y z : ℝ, x > 0 ∧ y > 0 ∧ z > 0 → (x^2 + y^2 + z^2) / (x * y + y * z + z * x) ≥ 1 + (x + y) / z + (z + x) / y + (y + z) / x - 4 * (x / (y + z) + y / (z + x) + z / (x + y)) := by sorry