Take the same partial fractions expression as before, but write it as
Then expand the expression in square brackets using the binomial series.
For (c), go back to the original expression . To expand this in powers of z, you would need a series in positive powers of z if you wanted it to converge when |z| < 1. But the question asks for an expansion valid when |z| > 1, so you must use negative powers of z. Write the function as and again use the binomial expansion of the expression in the square brackets.