If a,b,c are positive real numbers such that a+b+c=6 then
b(a−b)2+c(b−c)2+a(c−a)2+2(ab+bc+ca)≥24
Your inequaity equivalent to
b(a−b)2+c(b−c)2+a(c−a)2+a+b+c12(ab+bc+ca)⩾4(a+b+c), or
abc(ab+bc+ca)c(a2−2ab+bc)2+a(b2−2bc+ca)2+b(c2−2ca+ab)2⩾0. Done.
Source: InternLM Lean-Workbook, record lean_workbook_21064 (Apache-2.0). Complete source proposition preserved; proof developed independently.
Preamble
import Mathlib
open Real Nat
Formal statement
theorem WorkbookSource.base_21064 (a b c : ℝ) (ha : 0 < a) (hb : 0 < b) (hc : 0 < c) (habc : a + b + c = 6) : (a - b) ^ 2 / b + (b - c) ^ 2 / c + (c - a) ^ 2 / a + 2 * (a * b + b * c + c * a) ≥ 24 := by sorry