Answer the following with reference to the idea of the middle term in a binomial expansion.
(i) For the expansion (a+b)n, state which term(s) are called the middle term(s) when
(a) n is even, and
(b) n is odd.
(ii) For the expansion (1+x)7, write down the ordinal number(s) (position in the sequence of terms) of the middle term(s). Do not evaluate the terms.
(iii) For the expansion (1+x)8, write down the ordinal number of the middle term and express this term symbolically in the form (rn)an−rbr by specifying suitable n,r,a, and b. Do not simplify.