For the quadratic equation (3a−1)x2+2(2a+1)x+(a−4)=0, a is a real parameter.
a. (i) Write the discriminant D in terms of a.
b. (ii) Determine all real values of a for which the equation has equal real roots.
c. (iii) For the value(s) of a obtained in part (ii), find the repeated root of the equation.