Answer the following questions related to quadratic expressions:
(i) Prove that for any real number k, the polynomial x2+2kx+k2 can be expressed as the square of a linear polynomial in x.
(ii) Using the result of part (i), show that 4x2+12xy+9y2 can be expressed as the square of a binomial in x and y.
(iii) Hence or otherwise, determine the value of m for which the polynomial 4x2+12xy+9y2−m is exactly divisible by the binomial x+23y.