Determining a function value from a linear equation

Proved

WorkbookSource.problem_39372

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Let $f:\mathbb R\to\mathbb R$ satisfy $4f(-1)=2f(-1)+2$ . Then

f(-1)=1.

Source: InternLM Lean-Workbook, record lean_workbook_39372 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_39372 (f : ℝ → ℝ) (h : 4 * f (-1) = 2 * f (-1) + 2) : f (-1) = 1  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_39372; Apache-2.0

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