# Homework Help: Determine the Laplace transform for the following functions

1. Nov 30, 2016

### eehelp150

1. The problem statement, all variables and given/known data
Can someone check my work?

2. Relevant equations

3. The attempt at a solution
1. $\frac{1}{s+2}+\frac{1}{s^2+1}$
2. $\frac{2}{s}+\frac{3}{s+4}$
3. $\frac{s*sin(-2)+cos(-2)}{s^2+1}$
4. $\frac{1}{(s+1)^2}$
5. Don't really know how to do this one...

2. Nov 30, 2016

### rude man

3. Nov 30, 2016

### eehelp150

f(t-T)u(t-T) = $e^{-as}F(s)$
$F(s)=\frac{s(sin(-2)+cos(-2)}{s^2+1}$
3. $\frac{e^{-2s}*s*sin(-2)+cos(-2)}{s^2+1}$

5. $(\frac{-5}{3s^2}+\frac{5}{s}) - ((\frac{-5}{3s^2}+\frac{7}{s})*e^{-4.2s})$

4. Nov 30, 2016

### rude man

\$3 you copied F(s) incorrectly. Correct it first.
#5 looks OK now but I don't have time right now to be sure.

5. Nov 30, 2016

### eehelp150

a = 1, b=-2
What did I do wrong?
$F(s)=\frac{s*sin(-2)+cos(-2)}{s^2+1}$

6. Dec 1, 2016

### rude man

Nothing. Sorry! But the exp(-2s) factor has to include all of F(s), i.e. you need another bracket. (Your post 3, prob. 3).
I think you have the hang of it. Good work.

7. Dec 1, 2016

thank you!