The correct answer is 4. Any x-values that result in the denominator being equal to 0.
When finding the domain of the quotient of two functions, we need to consider the domains of both the numerator and the denominator. The domain of a function is the set of all possible input values for which the function is defined. For the quotient of two functions, this means that the domain is the set of all x-values that are in the domains of both the numerator and denominator.
However, there is one additional restriction on the domain of the quotient of two functions. The denominator of the quotient cannot be equal to 0, because division by 0 is undefined. Therefore, any x-values that result in the denominator being equal to 0 are not included in the domain of the quotient.
In summary, the x-values that are not included in the domain of the quotient of two functions are any x-values that result in the denominator being equal to 0.