Let A be an n×n matrix over R with
p(λ)=λn+cn−1λn−1+⋯+c1λ+c0
as its characteristic polynomial. The Cayley-Hamilton Theorem states that p(A)=0. Use this fact to prove that the components xj(t) of the solution x(t) to the linear system x′=Ax satisfy the nth order equation
p(D)u=u(n)+cn−1u(n−1)+⋯+c1u′+c0u=0.