If a is a real number and a cubic equation
f(x) = x^3 − 8x^2 + (a+12)x − 2a
has a repeated root, what is the sum of all the possible values of a?
f(x) = x^3 − 8x^2 + (a+12)x − 2a
has a repeated root, what is the sum of all the possible values of a?