What the answer to 3rd degree;1/3 and-2square root3 are zeros;f(0)=-12?

f(x) = (x - 1/3)(x + 2root3)(x - a)

f(0) = -12

Therefore: - 12 = (-1/3)(2root3)(-a)

a = - 18/(root3) = -6(root3).