lean_workbook_plus_81985
ProvedLet and you get: which is true by AM-GM.
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_81985 (x y z : ℝ) : 4 * x^4 * z^2 + 4 * y^4 * x^2 + 4 * z^4 * y^2 + x^4 * y^2 + z^4 * x^2 + y^4 * z^2 ≥ 15 * x^2 * y^2 * z^2 := by sorry
Source