Theorem 3. Let A be an n × n matrix, and let f (λ) and g(λ) be two polynomials that are relatively prime. Moreovr, let x be a vector satisfy- ing f (A) g(A) x = 0. Then there exists a unique pair of vectors y, z such that f (A) y = 0, g(A) z = 0, and y + z = x. In other words, ker(f (A) g(A)) = ker f (A) ⊕ ker g(A).