by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
assume , b≤max(a,c) and b≥min(a,c) \n =>a(b−a)(b−c)≤0⟺a2b+abc≥ab2+ca2(1)
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_31707 (a b c : ℝ)
(h₀ : b ≤ max a c)
(h₁ : b ≥ min a c) :
a * (b - a) * (b - c) ≤ 0 ↔ a^2 * b + a * b * c ≥ a * b^2 + c * a^2 := by sorry