int(x^(2)dx)/(x^(4)+1)

int (x^(2))/(x^(4)+1)dx=

int(x^(2))/(x^(4)-1)dx

int((x^(2)+1)dx)/(x^(4)+1)

If I_(1)=int_(0)^(oo) (dx)/(1+x^(4))dx and I_(2)=underset(0)overset(oo)int x^(2)(dx)/(1+x^(4))"then"n (I_(1))/(I_(2))=

int(x^(2))/(1-x^(4))dx

int (x^(2) +1)/(x^(4) + x^(2) + 1) dx =

int(x^(2))/((x^(2)+1)(x^(2)+4))dx

int(x^2dx)/(x^4+x^2+1)

int ((x^(2)-1)dx)/(x^(4) + x^(2) + 1)

int ((x^(2)-1)dx)/(x^(4)+x^(2)+1)