English
The field ℂ is algebraically closed; every nonconstant polynomial with complex coefficients has a root in ℂ (the Fundamental Theorem of Algebra).
Русский
Поле ℂ алгебраически замкнуто; любой ненулевой многочлен с коэффициентами в ℂ имеет корень в ℂ (ФТА).
LaTeX
$$$$ \\forall p \\in \\mathbb{C}[X],\\ p \\text{ nonconstant } \\Rightarrow \\exists z \\in \\mathbb{C}, p(z)=0. $$$$
Lean4
instance isAlgClosed : IsAlgClosed ℂ :=
IsAlgClosed.of_exists_root _ fun _p _ hp => Complex.exists_root <| degree_pos_of_irreducible hp