Recent content by mazzo

thanks for this. But I found that when I substituted in this value for u it doesn't work. I tried x^2 = t 2xdx = dt xdx = dt/2 then \int \frac{x}{a^2+x^2}dx = \frac{1}{2} \int \frac{dt}{(a^2+t)} = \frac{1}{2}\ln|a^2+x^2|+c can I do the last step, is this...

Dear Forum, I've been trying to find a proof for the following: \int \frac{x}{a^2+x^2}dx = \frac{1}{2}\ln|a^2+x^2|+c After many hours I've resorted to asking for help - any ideas anyone? cheers, mazzo