integral -oo, oo [(2x)/(x^2+1)^2] dx

Question

(a) state why the integral is improper or involves improper integral
*infinite limit of integration
(b) determine whether the integral converges or diverges
converges?
(c) evaluate the integral if it converges
I know f(x)=arctan->f'(x)=1/(1+x^2)
I'm not sure what I do with the 2x in the numerator and the squared demoninator.