## anonymous 4 years ago hey im stuggling on a question, can someone please help how do you get from x(t) = e^(-t/3)u(t) to X(s) = 3/(3s + 1) x

1. anonymous

laplace transform?

2. anonymous

yeah but can not seem to get the answer. Help? I am really struggling x

3. anonymous

$\large{L(e^{-{\frac{t}{3}}}u(t))= \frac{1}{s+\frac{1}{3}}}= \frac{3}{3s+1}$

4. amistre64

hmm, not to adept with these, but it looks like maybe: $-\frac{1}{3}t-st=-t(s+\frac{1}{3})$ how you get to Lanas I aint got no clue :) but afterwards you can simplify it by mutliplying at all by 3/3

5. anonymous

but u cant have t's in X(s)?

6. amistre64

right, which is the part im not to adept at ;)

7. anonymous

How would you show this from first principles? x

8. amistre64

ack!!

9. amistre64

pauls online notes has some good material

10. anonymous

im not sure i did it right either, what i did was laplace(e^(-t/3)) ...

11. amistre64
12. anonymous

$e^{-\alpha t}u(t)= \frac{1}{s+ \alpha}$