 Complex conjugate root theorem

In mathematics, the complex conjugate root theorem states that if "P" is a polynomial in one variable with real coefficients, and "a" + "bi" is a root of "P" with "a" and "b" real numbers, then its complex conjugate "a" − "bi" is also a root of "P".It follows from this (and the fundamental theorem of algebra), that if the degree of a real polynomial is odd, it must have at least one real root.