Determinar una raíz de la siguiente ecuación
de variable “x”: x2 + (3a  -  2b)x  -  6ab = 0

Using the "ac" method, we determine whcih 2 factors, when multiplied, gives "ac," or - 6ab. 
Furthermore, the same 2 factors sum to "b", or 3a - 2b. These 2 factors are: + 3a and - 2b
Rewrite the equation, substituting + 3ax - 2bx for (3a - 2b)x, to get: 
x(x + 3a) - 2b(x + 3a) = 0
(x - 2b)(x + 3a) = 0
x - 2b = 0          OR          x + 3a = 0 ----- Setting each factor equal to 0.
     OR
       OR              