lean_workbook_plus_10305

Proved

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

Let $P(x,y)$ be the assertion $f(x+y-f(xy))=f(1-x)f(y)+f(x)$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_10305 (f : ℝ → ℝ) (hf: f = fun x ↦ x) : ∀ x y, f (x + y - f (x*y)) = f (1 - x) * f y + f x   :=  by sorry

Source