Evaluate the rational expression below at $x=-1$.
$\frac{12}{x+3}$

Simplify each expression.

$\frac{x^2-10x+24}{(4-x)(6-x)}$

For which of the following values of $x$ is the rational expression undefined?

$\frac{5}{x}$

For which of the following values of $x$ is the rational expression undefined?

$\frac{7}{x-3}$

For which of the following values of $x$ is the rational expression undefined?

$\frac{x+1}{x^2-9}$

Evaluate the rational expression below at $x=2$.

$\frac{x^2-4}{x^2-x-6}$

Evaluate the rational expression below at $x=-2$.

$\frac{3x}{x^2+x-6}$

Simplify the rational expressions below:

$\frac{6x}{12x}$

Simplify the rational expressions below:

$\frac{x^2-9}{x^2-3x}$