by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
Thus, it remains to prove that 7(x3+y3+z3)2≥(x5+y5+z5)(x+y+z)+2(x2y2+x2z2+y2z2)(x+y+z)2 , which is ∑sym(3x6−x5y−2x4y2+5x3y3−4x3y2z−x2y2z2)≥0 , which is obvious.
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_62493 : ∀ x y z : ℝ, 7 * (x ^ 3 + y ^ 3 + z ^ 3) ^ 2 ≥ (x ^ 5 + y ^ 5 + z ^ 5) * (x + y + z) + 2 * (x ^ 2 * y ^ 2 + x ^ 2 * z ^ 2 + y ^ 2 * z ^ 2) * (x + y + z) ^ 2 := by sorry