lean_workbook_plus_31366

Proved

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

What is the value of $(-9)^2$ ?

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_31366 : (-9)^2 = 81   :=  by sorry

Source