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- #1
- Apr 13, 2013
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Hi!!! 
I have to find the Laplace transform of the function $tcos(wt) , w>0 $ .
That's what I have done so far:
$I=\int_{0}^{\infty}e^{-st}tcos(wt)dt=\int_{0}^{\infty}(\frac{-e^{-st}}{s})'tcos(wt)dt=\left [(\frac{-e^{-st}}{s})tcos(wt) \right ]_{0}^{\infty}-\int_{0}^{\infty}(\frac{-e^{-st}}{s}(cos(wt)-sin(wt))dt $
How can I find the limit,when $t\to \infty$ ?
I have to find the Laplace transform of the function $tcos(wt) , w>0 $ .
That's what I have done so far:
$I=\int_{0}^{\infty}e^{-st}tcos(wt)dt=\int_{0}^{\infty}(\frac{-e^{-st}}{s})'tcos(wt)dt=\left [(\frac{-e^{-st}}{s})tcos(wt) \right ]_{0}^{\infty}-\int_{0}^{\infty}(\frac{-e^{-st}}{s}(cos(wt)-sin(wt))dt $
How can I find the limit,when $t\to \infty$ ?