Isolating a summand in a zero sum

Proved

WorkbookSource.problem_39348

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

lean-workbooksource-checked

For real numbers $a,b,c$ with $a+b+c=0$ ,

b=-a-c.

Source: InternLM Lean-Workbook, record lean_workbook_39348 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_39348 (a b c : ℝ) (h : a + b + c = 0) : b = -a - c  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_39348; Apache-2.0

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