Solution 2.9.5.3
Applying the Laplace transform yields
s
2
Y (s);sy(0);y
[1]
(0)+ 2[sY (s);y(0)];8Y (s)=0:
Rearranging yields
(s
2
+2s;8)Y (s)=sy(0)+ 2y(0)+ y
[1]
(0);;
or
Y (s)=
sy(0)+ 2y(0)+ y
[1]
(0)
(s
2
+2s;8)
For the given initial conditions we then have
Y (s) =
s +10
(s + 2)(s;4)
=
A
s +2
+
B
s;4
:
A = (s +2)Y (s)
s=;2
=
s +10
(s;4)
s=;2
= ;4=3
B = (s;4)Y (s)
s=4
=
s +10
(s +2)
s=4
= 7=3
f(t)=[(7=3)e
4t
;(4=3)e
;2t
]1(t):
1