## anonymous 3 years ago Determine the Laplace transform$\large e^{-t} \space t \space \sin2t$$f(t)=t \space \sin2t$$L[e^{-t}f(t)]=L[f(t)](s+1)$My Answer$\frac{ 4s(s+1) }{ (s^2+4)^2 }$Book Answer$\frac{ 4(s+1) }{ [(s+1)^2+4]^2 }$What am I missing?

1. anonymous

@zepdrix You feel like looking at another one?

2. zepdrix

Hmmm I dunno, I gotta get caught up on my Diff EQ homework apparently XD lol

3. anonymous

I have a Laplace test tomorrow and I'm just going back thru all the study problems. I feel like I did this right. I don't know. What year are you in school @zepdrix

4. zepdrix

Mmmmm i dunno, almost done with 2 years i guess :O not too far in yet.

5. anonymous

6. zepdrix

Pshhhh i dunno, I'll figure that out next semester.. trying to put it off as long as i can, until i absolutely have to decide XD I love love love math.. i can't seem to narrow it down any further than that :D

7. anonymous

Haha, took me 4 years and a couple of different majors before I landed on engineering. I might post more Laplace questions. stay tuned

8. AccessDenied

Here is what I did to get the book answer: http://mathbin.net/114299

9. anonymous

@AccessDenied Thank you for the solution. I'll study that for future problems :)

10. anonymous

simplify $(\sqrt x+\sqrt 3)(\sqrt x+\sqrt 27)$$(\sqrt x \times \sqrt x)+(\sqrt x \times \sqrt 27)+(\sqrt 3 \times \sqrt x)+(\sqrt 3 \times \sqrt 27)$$x+\sqrt {27x}+\sqrt {3x}+[\sqrt {3 \times 27}=\sqrt {81}=9]$@lala2

11. anonymous

thanks so much @ChmE!

12. anonymous

yup