Use the functions below to answer the questions that follow. $$\begin{aligned} P(x)\amp=\sqrt{10x - 1}\\ R(x)\amp=\frac{x-3}{x^2-64} \end{aligned}$$

1. For the function $P\text{,}$ the domain is all real numbers ? greater than less than greater than or equal to less than or equal to .
2. For the function $R\text{,}$ find a number that is not in the domain. Answer: