Express in partial fractions and hence obtain f(x) as a series in ascending powers of x, giving the first 3 non-zero terms of this expansion. Find the coefficient of in the expansion.

Express as partial fractions and hence obtain f(x) as a series in ascending powers of x as far as the term x³. State the range of values of x for which the expansion is valid. Find the coefficient of in the expansion, where n>1.