Answer: {0, -4}
Step-by-step explanation: Notice that the two terms on the left side
of the equation have a greatest common factor of 6x.
So start by factoring out a 6x to get 6x(x + 4) = 0.
So either 6x = 0 or x + 4 = 0.
Eventually we find that x = 0 or x = -4.
So our solution set is {0, -4}.
