Example 12.11.   Show that  [Graphics:Images/LaplaceTransformMod_gr_170.gif].  

Explore Solution 12.11.

Method 1.  Enter the function  [Graphics:../Images/LaplaceTransformMod_gr_177.gif]  and compute the integral defining   [Graphics:../Images/LaplaceTransformMod_gr_178.gif].  

[Graphics:../Images/LaplaceTransformMod_gr_179.gif]




[Graphics:../Images/LaplaceTransformMod_gr_180.gif]

 

 

 

 

Assuming that f(t) is of exponential order, we have  [Graphics:../Images/LaplaceTransformMod_gr_181.gif]. Then  [Graphics:../Images/LaplaceTransformMod_gr_182.gif],  and the Laplace transform can be computed by the calculation  [Graphics:../Images/LaplaceTransformMod_gr_183.gif].

[Graphics:../Images/LaplaceTransformMod_gr_184.gif]





[Graphics:../Images/LaplaceTransformMod_gr_185.gif]



Method 2.  Since  [Graphics:../Images/LaplaceTransformMod_gr_186.gif],  we can use  [Graphics:../Images/LaplaceTransformMod_gr_187.gif].  

[Graphics:../Images/LaplaceTransformMod_gr_188.gif]




[Graphics:../Images/LaplaceTransformMod_gr_189.gif]

 

 

 

 

Aside. We can check this with Mathematica's  result using the LaplaceTransform package.

[Graphics:../Images/LaplaceTransformMod_gr_190.gif]




[Graphics:../Images/LaplaceTransformMod_gr_191.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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