The function $$f\left( z \right) = {{{z^2} + 1} \over {{z^2} + 4}}$$ is singular at

The value of the expression $${{ - 5 + 10i} \over {3 + 4i}}$$ is

If a complex number $$z = {{\sqrt 3 } \over 2} + i{1 \over 2}$$ then z⁴ is

The function $$$w = u + iv = {1 \over 2}\log \left( {{x^2} + {y^2}} \right) + i{\tan ^{ - 1}}\left( {{y \over x}} \right)$$$ is not analytic at the point.