Example 9.14.  Solve  [Graphics:Images/ZTransformDEMod_gr_74.gif]   with  [Graphics:Images/ZTransformDEMod_gr_75.gif].  

[Graphics:Images/ZTransformDEMod_gr_76.gif]

Solution 9.14.

    The characteristic equation  [Graphics:../Images/ZTransformDEMod_gr_77.gif]  has complex roots [Graphics:../Images/ZTransformDEMod_gr_78.gif] and [Graphics:../Images/ZTransformDEMod_gr_79.gif] hence the general solution is  [Graphics:../Images/ZTransformDEMod_gr_80.gif].   Use the initial conditions and form the linear system  

        [Graphics:../Images/ZTransformDEMod_gr_81.gif]

        [Graphics:../Images/ZTransformDEMod_gr_82.gif]  

then solve for the constants and get [Graphics:../Images/ZTransformDEMod_gr_83.gif] and [Graphics:../Images/ZTransformDEMod_gr_84.gif].  Hence the solution is

        [Graphics:../Images/ZTransformDEMod_gr_85.gif].

We leave it for the reader to verify that this can be written as  

        [Graphics:../Images/ZTransformDEMod_gr_86.gif].

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2006 John H. Mathews, Russell W. Howell