>>246

(1+x^2)/(1-x^2)
=-1 +2/(1-x^2)
=-1 -2/(x^2-1)
=-1 -{1/(x-1) -1/(x+1)}

∫dx=x
∫1/(x-1) dx=log|x-1|
∫1/(x+1) dx=log|x+1|
を使えばできる