by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)
Let a+b=s,ab=t with s,t>0 and s2≥4t , thus \n\n (x2+ab)2(a+b)2−4ab(x2+a2)(x2+b2) \n\n =s2(x2+t2)2−4t{x4+(s2−2t)x2+4t2} \n\n =(s2−4t)x4−2t(s2−4t)x2+t2(s2−4t) \n\n =(s2−4t)(x2−t)2≥0.
Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_54037 (a b s t x : ℝ)
(h₀ : 0 < a ∧ 0 < b)
(h₁ : a + b = s)
(h₂ : a * b = t)
(h₃ : s^2 ≥ 4 * t)
: (x^2 + a * b)^2 * (a + b)^2 - 4 * a * b * (x^2 + a^2) * (x^2 + b^2) ≥ 0 := by sorry