lean_workbook_plus_14023

Proved

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

Divide both sides of the equation by $3$ : \n\n $x^2 + 6x + 9 = 0 \Rightarrow\n(x + 3)^2 = 0$ \n\nSo $x = \boxed{-3}$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_14023  (x : ℝ)
  (h₀ : x^2 + 6 * x + 9 = 0) :
  x = -3   :=  by sorry

Source