lean_workbook_plus_4559

Proved

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

Let $x$ and $y$ be positive real numbers with $x^3 + y^3 = x - y.$ Prove that $x^2 + y^2 < 1.$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_4559 (x y : ℝ) (hx : 0 < x) (hy : 0 < y) (h : x^3 + y^3 = x - y) : x^2 + y^2 < 1   :=  by sorry

Source