My desk of Integrals has the final case ##int frac dx x^2+a^2 ## as being a 'common' integral far too, not merely the situation where ##a=1##. But I do think this becoming a Calculus homework difficulty it is anticipated in the OP to figure out how to get it done. https://gabletoppak.com/kerala-get-ready-to-say-no-to-plastic-from-october-2/