I'll focus on the parts circled in red.
We have this function [tex]\text{r}(\text{x}) = \frac{\text{x}+13}{\text{x}-3}[/tex]
Question 6 asks what value of x is not allowed. That would be 3 since it causes the denominator to turn into zero. Dividing by zero is not allowed.
[tex]\text{x}-3= 3-3 = 0[/tex]
So we must kick [tex]\text{x} = 3[/tex] out of the domain. Any other value of x is allowed.
Final Answer: 3
