For each expression given below, carry out the tasks mentioned in parts (i) to (iii):
(i) Rewrite the expression, if necessary, so that it contains no zero–coefficient terms and is arranged in descending powers of the variable.
(ii) State the number of non-zero terms in the rewritten expression.
(iii) Classify the expression obtained in part (i) as a monomial, binomial or trinomial, and write its degree.