越出方程的解 2()= 2 s(S+1)2+1 3拉氏递变换 2()=L[2(s)]=[-esim()(t)求出方程的解 ( 1) 1 2 1 1 ( ) 2 2 + + = − s S u s 3.求拉氏逆变换 sin( )] ( ) 2 1 ( ) [ ( )] [ 2 1 2 u t L u s e t u t − −t = = −