lean_workbook_plus_23098

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

How can you get that $x^8-x^7+x^2-x \geq -4$ for $-1 \leq x \leq 1$ ?

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_23098 (x : ℝ) (hx : -1 ≤ x ∧ x ≤ 1) :
  x^8 - x^7 + x^2 - x ≥ -4   :=  by sorry

Source