For each of the following expressions in the variable x, answer the questions that follow:
(a) 4x3−2x2+x−1
(b) 0
(c) 5x−1+2
(d) 7x21−3
(e) 9
a. (i) State, with a reason in each case, whether the given expression is a polynomial in x.
b. (ii) For every expression that is a polynomial, write its degree.
c. (iii) Arrange the polynomials identified in part (ii) in descending order of degree and state whether each is a monomial, binomial or trinomial.