My table of Integrals has the overall case ##int frac dx x^2+a^2 ## for a 'standard' integral as well, not only the situation where by ##a=1##. But I feel this being a Calculus homework challenge it is predicted in the OP to determine how to do it. Hints were given https://gabletoppak.com/how-gabletop-cartons-are-helping-water-brands-combat-climate-change/