取A=DX@即得结论的证明。 充分性。由假设得 X(t)=eAt 从而有 X(t+5)=e4(+4)=eMte4.=X(t)X(s). 证毕  A = DX(0) dt =(ÿy²" ø©5"db X(t) = e At l k X(t + s) = e A(t+s) = e Ate As = X(t)X(s). y. 7