Integral of an exponential function

asi123
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Homework Statement



Hey guys.

How do I solve this integral?

http://img816.imageshack.us/img816/208/68315659.png

I've not been doing this for a long time :)

Thanks a lot.


Homework Equations





The Attempt at a Solution

 
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Show some work, and explain what tools you have to work with. Definite integrals can be computed in many ways.
 


You can use integration by parts. Using u = e^-t and dv = t^-2 dt
 


JetteroHeller said:
You can use integration by parts. Using u = e^-t and dv = t^-2 dt

Yeah, but then I'll get some kind of Ln(t)*e^-t, no?
 


Actually you may want to check convergence.
 


I was actually thinking:
you perform integration by parts once to reduce t^2 to t.
Result is that one of the terms is integral((e^-t)/t)
Rewrite that term to become integral(1/te^t)

use the following identity from integral tables: integral(ue^u) = (u-1)e^u
the rest is taking limits.
 
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