by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
Identity for a,b,c (even if a+b+c=1 ): 10(a3+b3+c3)(a+b+c)2−9(a5+b5+c5)=(a+b+c)5+215(a+b)(a+c)(b+c)((a−b)2+(a−c)2+(b−c)2)
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_5559 (a b c : ℝ) :
10 * (a^3 + b^3 + c^3) * (a + b + c)^2 - 9 * (a^5 + b^5 + c^5) =
(a + b + c)^5 + (15 / 2) * (a + b) * (a + c) * (b + c) * ((a - b)^2 + (a - c)^2 + (b - c)^2) := by sorry