lean_workbook_plus_11863

Proved

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

Prove the equality $(x+y)(y+z)(z+x)=(x+y+z)(xy+yz+zx)-xyz$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_11863 (x y z : ℝ) : (x + y) * (y + z) * (z + x) = (x + y + z) * (x*y + y*z + z*x) - x*y*z   :=  by sorry

Source