Find the range of f(x)=\ac11+x2f(x) = \ac{1}{1+x^2}f(x)=\ac11+x2.
(0,1](0, 1](0,1]
[0,1][0, 1][0,1]
(0,\nfty)(0, \nfty)(0,\nfty)
All real numbers