• Support PF! Buy your school textbooks, materials and every day products Here!

Reducing final answer of laplace transform

  • Thread starter xtipd
  • Start date
  • #1
7
0

Homework Statement


The problem is not getting the answer to the laplace transform but instead reducing my answer so i dnt lose marks.

If i work out the laplace transform of:
L(t^3 * sinh(4t)) to be
3!/(2(s- 4)^4)- 3!/(s(s+ 4)^4) then how do i add these to get a single fraction? Its doing my head in

The Attempt at a Solution


I know something has to be multiplied but i have no idea what it is...

Thanks in advance!
 

Answers and Replies

  • #2
gabbagabbahey
Homework Helper
Gold Member
5,002
6

Homework Statement


The problem is not getting the answer to the laplace transform but instead reducing my answer so i dnt lose marks.

If i work out the laplace transform of:
L(t^3 * sinh(4t)) to be
3!/(2(s- 4)^4)- 3!/(s(s+ 4)^4) then how do i add these to get a single fraction? Its doing my head in

The Attempt at a Solution


I know something has to be multiplied but i have no idea what it is...

Thanks in advance!
Did you mean [itex]\mathcal{L}[t^3 \sinh(4t)]=\frac{3!}{2(s- 4)^4}- \frac{3!}{2(s+ 4)^4}[/itex]?

If so, the first thing to do would be get rid of the factorials; [itex]3!=3*2[/itex] and then cancel the 2 in the denominators.


Next, multiply the first fraction (numerator and denominator) by [itex](s+4)^4[/itex] and the second fraction (numerator and denominator) by [itex](s-4)^4[/itex]

Then expand out the numerator and simplify.

You can also simplify the common denominator by noting that [itex](s+4)^4(s-4)^4=[(s+4)(s-4)]^4=(s^2-16)^4[/itex]
 
  • #3
7
0
Yeh thats what i meant.

Awsome, cheers for the help!

thought it was something like that
 

Related Threads for: Reducing final answer of laplace transform

  • Last Post
Replies
2
Views
962
Replies
1
Views
921
Replies
3
Views
1K
Replies
0
Views
952
  • Last Post
Replies
3
Views
532
  • Last Post
Replies
5
Views
796
  • Last Post
Replies
3
Views
12K
  • Last Post
Replies
5
Views
5K
Top