The values that would be excluded from the domain of the function are those that create vertical asymptotes in the graph.
Vertical asymptotes can be found by setting the expression in the denominator equal to 0 (zero) and solving for x. The resulting values of x are the values that are excluded from the domain of the function.
Expression in the denominator = x^2 - 5x + 6
x^2 - 5x + 6 = 0
(Factor to solve)
(x - 3)(x - 2) = 0
x - 3 = 0 || x = 3
x - 2 = 0 || x = 2
The values that are excluded from the domain of the function are 3 and 2.
Hope this helps!