Notice that
4(x/(1-x^4))=2x/( (x^2+1))-1/( (x-1))-1/( (x+1))4(x1−x4)=2x(x2+1)−1(x−1)−1(x+1)
Hence
int x/(1-x^4)dx=2int x/( (x^2+1))dx-int1/( (x-1))dx-int1/( (x+1))dx=log(x^2+1)-log(x-1)-log(x+1)+c=
log(x^2+1)-log(x^2-1)+c∫x1−x4dx=2∫x(x2+1)dx−∫1(x−1)dx−∫1(x+1)dx=log(x2+1)−log(x−1)−log(x+1)+c=log(x2+1)−log(x2−1)+c