Example 4: Find F(s) f(t) 3 3 3-23-23 Solution: f(t)==tu(t) ()-tu(t-2)+3u(t-2) 2 =t()-(t-2)u(t-2)-3u(t-2)+3(t-2) t() (t-2)u(t-2) 31 S)=-× 3-232 3Example 4: Find F(s) ( 2) 3 ( 2) 2 3 ( ) 2 3 f (t) = tu t − tu t − + u t − ( 2) ( 2) 3 ( 2) 3 ( 2) 2 3 ( ) 2 3 = t u t − t − u t − − u t − + u t − ( 2) ( 2) 2 3 ( ) 2 3 = tu t − t − u t − ( e ) s e s s F(s) s 2s 2 2 2 2 1 2 1 3 2 1 3 2 3 − − =  −  = − Solution: 2 3 f (t) t