find a greatest common divisor, d(x), for each of the following pairs of polynomials and express d(x) as a polynomial combination of the given pair: (i) the polynomials x 3 i and x 2 x - i over jr; (ii) the polynomials x 4 x l and x 3 x l over z2; (iii) the polynomials x 3 - ix 2 2x - 2i and x 2 l over c.