My Desk of Integrals has the overall scenario ##int frac dx x^2+a^2 ## being a 'conventional' integral way too, not only the case exactly where ##a=1##. But I do think this currently being a Calculus homework problem it is expected on the OP to figure out how to get it https://gabletoppak.com/kerala-get-ready-to-say-no-to-plastic-from-october-2/