∫ 1/[x(x^n+a)] dx= (1/a)∫ a/[x(x^n+a)] dx= (1/a)∫ [(x^n+a)-x^n]/[x(x^n+a)] dx= (1/a)∫ (x^n+a)/[x(x^n+a)] dx - (1/a)∫ x^n/[x(x^n+a)] dx= (1/a)∫ 1/x dx - (1/a)∫ x^(n-1)/(x^n+a) dx= (1/a)∫ 1/x dx...
