Using the identity (1+x²)/(1+x⁴)=(1)/(2)((1)/(1+ √x+x²)+(1)/(1- √x+x²)), which you do not have to prove, show that int_0¹ (1+x²)/(1+x⁴)dx=(1)/(2) int_(-1)¹ (dx)/(1+ √x+x²)+(1)/(1- √x+x²)