- #1

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## Homework Statement

##\displaystyle \int \frac{1}{x^2+a} dx##

## Homework Equations

## The Attempt at a Solution

I know that I can convert this to the form ##\displaystyle \int \frac{1}{x^2+(\pm \sqrt{a})^2} dx## = ##\displaystyle \frac{1}{\pm \sqrt{a}} \arctan (\frac{x}{\pm \sqrt{a}}) + C##, but I don't know whether to take the positive or the negative root.