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kirbykirby
 4 years ago
Integral! (related to gamma function maybe?)
\[\int\limits_{0}^{X}\frac{\lambda^3}{2}t^2e^{\lambda t}dt
kirbykirby
 4 years ago
Integral! (related to gamma function maybe?) \[\int\limits_{0}^{X}\frac{\lambda^3}{2}t^2e^{\lambda t}dt

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kirbykirby
 4 years ago
Best ResponseYou've already chosen the best response.0Here it is: \[\int\limits_{0}^{X}\frac{\lambda^3}{2}t^2e^{\lambda t}dt\] I tried doing this trying to relate it to a gamma function but myupper bound is not infinity :S: \[=\frac{\lambda^3}{2}\int\limits_{0}^{X}t^2e^{\lambda t}dt\] \[Let : u=\lambda t =>t=u/t\]\[So: du=\lambda dt\]\[Bounds: u=0=>t=0 ; u=x=>t=x/\lambda\] \[\frac{\lambda^2}{2}\int\limits_{0}^{X/\lambda}(\frac{u}{\lambda})^2e^{u}du\]\[=\frac{1}{2}\int\limits_{0}^{X/\lambda}u^{31}e^{u}du\]

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0why do you not just use tabular method

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0it's a special type of by parts.. you can do by parts also

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0dw:1358916012425:dw

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0dw:1358916166540:dw

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0\[\int t^2e^{yt}=\frac{t^2e^{yt}}{y}\frac{2te^{yt}}{y^2}\frac{2e^{yt}}{y^3}+c\]

kirbykirby
 4 years ago
Best ResponseYou've already chosen the best response.0Hmm interesting o_o!! As I was trying to do integration by parts, I realized I have to do it twice. Is this method related to doing int. by parts multiple times?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=integral+of+t%5E2e%5E%7Byt%7D same answer as mine only simplified and yes Tabular method is when you have something of this sort \[\int t^nf(t)dt\] you take the derivatives of the t to thepower until you get to zero giving them alternating signs and integrate the f(t) one more time than how many it takes the t power function goes to zero

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0look up tabular method for a derivation of this

kirbykirby
 4 years ago
Best ResponseYou've already chosen the best response.0Oh wow this is quite neat !! :) thank you so much

kirbykirby
 4 years ago
Best ResponseYou've already chosen the best response.0I can't believe they never taught this technique..
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