4.延迟性质 设:[f(t)川=F(s) 则:[f(t-t)】=eF(s) 证、 当t<t时,f(t-to)=0,令t=t-t 则: f(t-t】=ft. f()edr ef()edr -e sF(S)4.延迟性质 设: [ f (t)] F(s) [ ( )] ( ) 0 0 f t t e F s st 则: 证 , ( ) 0 , 0 0 0 当 t t 时 f t t 令 t t (s) ( ) ( ) [ ( )] ( ) 0 0 0 0 0 ( ) 0 0 0 e F e f e d f e d f t t f t t e dt st st s s t st 则: