Multiple choice The analytic function f(z) = $\frac{z - 1}{z^2 + 1}$ has singularities at 1 and - 1 1 and i 1 and - i i and - i Reveal answer Fill a bubble to check yourself D Correct answer Explanation Singularities of a rational function occur where the denominator is zero. Setting z^2 + 1 = 0 leads to z^2 = -1, which gives z = i and z = -i.