A family of functions is defined by Gk(x)=x−kx2−4, where k is a real parameter.
a. (i) For which value(s) of k does Gk(x) represent a polynomial function? Give reasons.
b. (ii) When k=2, state the domain of G2(x) and decide whether G2(x) is a polynomial or a rational function.
c. (iii) For k=2, find the excluded value(s) of Gk(x) and comment on the nature of discontinuity at those point(s).