My table of Integrals has the final case ##int frac dx x^2+a^2 ## as being a 'conventional' integral far too, not only the case in which ##a=one##. But I think this remaining a Calculus homework difficulty it is anticipated in the OP to determine how to make it happen. Hints https://gabletoppak.com/chikkamagaluru-dc-to-declare-mullayyanagiri-hill-station-plastic-free-zone-on-world-earth-day/