Should be simple: int [ x / (x^2 + 4) ] dx

[xycos]

On a recent quiz in my class, one of the problems was to find the following indefinite integral:

. . .int [ x / (x^2 + 4) ] dx

The answer, as I found out later on my calclator, is:

. . .ln(x^2 + 4) / 2

However, I'm not sure how this result is discovered. Any help would be appreciated.

Thanks for reading,
Best of wishes,
xycos

 

[stapel]

What method did you use for doing this integration? (I would have tried using "u = x² + 4", so du = 2xdx and (1/2)du = xdx.)

Please reply with specifics. Thank you.

Eliz.

 

[xycos]

Heh, that was easy... thanks a lot for your help.