i(x,s)=Ae"+Be s(D2+s2) x=0=0,ix|x→to=0 A=0 1 B=-s(w2+s) i-ot1-e) 44 A 0 2 2 1 ( ) B s s 2 2 1 1 ( ) s x u e a s s 2 2 1 ( , ) ( ) s s x x a a u x s Ae Be s s u u x x x 0 0, 0 1 1 2 2 2 2 1 1 ( ) ( ) s x a u L u L e s s s s