Hi, I have the problem to find:
integral of - x.arctan (x)
the hint / first step is pointed to by first asking to find:
integral of - x^2 / ( 1 + x^2 )
I have found the answer to be:
1/2 ( x^2 +1 ) . arctan (x) - 1/2.x
I cannot deduce the working to get here though. Any help much...