Elizabeth X.

Which of the following are rational expressions?
$${ (a) } \frac{3 x}{x^{2}-1} \quad \text { (b) } \frac{\sqrt{x+1}}{2 x+3} \quad \text { (c) } \frac{x\left(x^{2}-1\right)}{x+3}$$

To multiply two rational expressions, we multiply their ______ together and multiply their ______ together.
So $\frac{2}{x+1} \cdot \frac{x}{x+3}$ is the same as ______.

Yes or No? If $N o,$ give a reason. (Disregard any value that makes a denominator zero.)
\begin{equation}
\begin{array}{l}{\text { (a) Is the expression } \frac{x(x+1)}{(x+1)^{2}} \text { equal to } \frac{x}{x+1} ?} \\ {\text { (b) Is the expression } \sqrt{x^{2}+25} \text { equal to } x+5 ?}\end{array}
\end{equation}

Find the domain of the expression.
$$4 x^{2}-10 x+3$$

Find the domain of the expression.
$$\frac{x^{2}-1}{x-3}$$

Find the domain of the expression.
$$\frac{x^{2}+1}{x^{2}-x-2}$$