Dangerous one.
See:
http://www.wolframalpha.com/input/?i=integrate+1%2Fsqrt%28x%28x%5E2%2B1%29%29
Dangerous one.
See:
http://www.wolframalpha.com/input/?i=integrate+1%2Fsqrt%28x%28x%5E2%2B1%29%29
I've 2 different solutions:
1) This
http://integrals.wolfram.com/index.jsp?expr=1%2F(x*Sqrt[x^2+%2B1])
2) And this (provided by my professor)