Question

can any body help me please?

Answer 1

For the first one, put z = a + ib where a and b are real and show that
\[
\frac{1}{1-a-i b}=\frac{1-a}{(1-a)^2+b^2}+\frac{i
b}{(1-a)^2+b^2}
\]
and conclude

Answer 2

To be able to show the above write
\[
\frac{1}{1-a-i b}=\frac{1 \times(1-a+i b)}{(1-a-i b) (1-a+i
b)}

\]
and expand