`I=int_(-oo)^(1)(1)/(x^(2))dx`

int_(0)^(oo)(1)/(3+x^(2))dx

int_(1)^(oo)(dx)/(x^(2))

int_(0)^(oo)((1)/(x^(2)+1))dx

int_(3)^(oo)(3)/(x^(2)-1)dx

Evaluate : (i) int_(-oo)^(oo) (dx)/(x^(2)+2x+2) , (ii) int_(sqrt(2))^(oo)(dx)/(xsqrt(x^(2)-1)) , (iii) int_(0)^(4)(x^(2))/(1+x)dx (iv) int_(0)^(pi//2) sqrt(costheta)sin^(3)theta

int_(1)^(oo) (1)/(1+x^(2)) dx =

int_(0)^(oo)(1)/(1+e^(x))dx=

int_(0)^(oo)(x)/(1+x^(4))dx=