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L { integral from 1 to t (xe^-x dx) }...
find F(s)

2007-04-18 18:11:38 · 4 answers · asked by wills 3 in Science & Mathematics Mathematics

4 answers

Integrating first,
let u = x, du = dx
dv = e^-xdx, v = - e^-x
giving
-xe^-x + ∫e^-xdx =
-(x + 1)e^-x
applying limits,
-(t + 1)e^-t + 1 =
1 - e^-t - te^-t
Applying the transforms,
1/s - 1/(s + 1) - 1/(s + 1)^2

2007-04-18 18:45:18 · answer #1 · answered by Helmut 7 · 0 0

Don't you have a transform pair table? I don't remember it off the top of my head (is it s or s² or 1/s) and my LaPlace Transform reference isn't here (it's in my office). Find it on the web.


Doug

2007-04-19 01:23:09 · answer #2 · answered by doug_donaghue 7 · 0 0

(-t-1)(e^-t) +2/e is the integral, idk the rest is what sry

2007-04-19 01:16:24 · answer #3 · answered by dpmwcml 2 · 0 1

tricky shtuff
i dunno

2007-04-19 01:28:04 · answer #4 · answered by steve 1 · 0 0

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