A cyclic quadratic ratio sum with a normalized product correction
ProvedWorkbookSource.plus_39495lean-workbooksource-checked
For prove that
Source: InternLM Lean-Workbook, record lean_workbook_plus_39495 (Apache-2.0). Complete source proposition preserved; proof developed independently.
Preamble
import Mathlib open Real Nat
Formal statement
theorem WorkbookSource.plus_39495 (a b c : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) : (a^2 + b^2 - a * (b - c)) / (b + c) / (c + a) + (b^2 + c^2 - b * (c - a)) / (c + a) / (a + b) + (c^2 + a^2 - c * (a - b)) / (a + b) / (b + c) + 2 * a * b * c / (a + b) / (b + c) / (c + a) ≥ 7 / 4 := by sorry
Source