lean_workbook_plus_61920

Proved

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

Let $P(x,y)$ be the assertion $f(x+y)+f(x-y)-2f(x)f(1+y)=2xy(3y-x^2)$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_61920 (f : ℝ → ℝ) (hf : ∀ x y, f (x + y) + f (x - y) - 2 * f x * f (1 + y) = 2 * x * y * (3 * y - x ^ 2)) : ∃ c, ∀ x, f x = c * x ^ 3   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

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