My table of Integrals has the final case ##int frac dx x^2+a^2 ## as a 'regular' integral much too, not simply the case in which ##a=1##. But I think this currently being a Calculus homework difficulty it is expected with the OP to figure out how to get it done. https://gabletoppak.com/how-gable-top-pak-can-enhance-your-brand-and-customer-experience/