81. $$\oint {\frac{{{{\text{z}}^2} - 4}}{{{{\text{z}}^2} + 4}}{\text{dz}}} $$ evaluated anticlockwise around the circle |z - i| = 2, where $${\text{i}} = \sqrt { - 1} ,$$ is
82. An analytic function f(z) of complex variable z = x + iy may be written as f(z) = u(x, y) + iv(x, y). Then, u(x, y) and v(x, y) must satisfy,
83. In the neighborhood of z = 1, the function f(z) has a power series expansion of the form $${\text{f}}\left( {\text{z}} \right) = 1 + \left( {1 - {\text{z}}} \right) + {\left( {1 - {\text{z}}} \right)^2} + \,...$$
Then f(z) is
Then f(z) is