using the Laplace transform to solve...

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• Apr 22nd 2011, 12:37 PM
slapmaxwell1
using the Laplace transform to solve...
man these problems are long but here goes...

ok i am not sure what im doing wrong but my partial fraction that I am getting is not giving me the right answer...one i have 7 terms and the book has 4 terms in its answer.

$2y'''+3y''-3y'-2y=e^{-t}$ y(0)=0, y'(0)=0 , y''(0)=1

after making the substitutions i got:

http://latex.codecogs.com/gif.latex?...ight)%20}-4]\]

i was hoping someone could tell me where i went wrong....

thanks
• Apr 22nd 2011, 12:40 PM
slapmaxwell1
• Apr 22nd 2011, 01:29 PM
Ackbeet
Hmm. Here's what I get:

http://quicklatex.com/cache3/ql_9689...fa03c03_l3.png

You can use the Heaviside cover-up method to get the constants, and then fire away with the inverse. As you can see, there are only 4 terms.

Does that help?
• Apr 22nd 2011, 01:31 PM
slapmaxwell1
ok i didnt get the 2s+3 let me go back and add that and finish working out the problem. thanks!
• Apr 22nd 2011, 01:32 PM
Ackbeet
You're welcome, as always.