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=one##. But I think this becoming a Calculus homework issue it is expected from the OP to figure out how to do it. Hints were https://gabletoppak.com/india-emerges-as-the-largest-plastic-polluter-globally/