The _____ _____ _____ states that if $f(x)$ is a polynomial of degree $n(n>0),$ then $f(x)$ has precisely $n$ linear factors, $f(x)=a_{n}\left(x-c_{1}\right)\left(x-c_{2}\right) \cdot \cdots\left(x-c_{n}\right),$ where $c_{1}, c_{2}, \ldots, c_{n}$ are complex numbers.