Homework Help: A stubborn integral

1. Jun 5, 2010

boa_co

1. The problem statement, all variables and given/known data
I have to integrate

[PLAIN]http://img69.imageshack.us/img69/4259/integral1.gif [Broken]

3. The attempt at a solution

This is how I did it

[PLAIN]http://img338.imageshack.us/img338/5508/integral12.gif [Broken]

wolfram says it is supposed to turnout like this

[PLAIN]http://img690.imageshack.us/img690/1462/integral13.gif [Broken]

Where does the extra 2 in the log come from?

Thanks

Last edited by a moderator: May 4, 2017
2. Jun 5, 2010

CompuChip

The answers are actually the same, up to a constant -2 ln(2).

With logarithms this is always tricky, because they satisfy
$$\ln(a \cdot b) = \ln(a) + \ln(b)$$

Apparently Wolfram Alpha / Mathematica uses some other method to calculate the integral in which the 2 inside the log appear naturally.