lean_workbook_plus_79703

Proved

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

Let $P(x,y)$ , be the assertion $f(f(x)+y)=f(x^2-y)+4yf(x)$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_79703 (f : ℝ → ℝ) (hf: f = fun x ↦ x^2) : ∀ x y, f (f x + y) = f (x^2 - y) + 4 * y * f x   :=  by sorry

Source