A quartic lower bound with mixed and linear terms

Proved

WorkbookSource.base_4495

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Prove that $x^4 + 5 + y^2 + y^4 \ge x^2 + 4y +2xy^2$ .

Source: InternLM Lean-Workbook, record lean_workbook_4495 (Apache-2.0). Complete source proposition preserved; proof developed independently.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.base_4495 (x y : ℝ) : x^4 + 5 + y^2 + y^4 ≥ x^2 + 4*y + 2*x*y^2  :=  by sorry

Source