Evaluate the rational expression below at $x=2$.
$\frac{x^2-4}{x^2-x-6}$

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 $x=-1$.

$\frac{12}{x+3}$

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:

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

Simplify the rational expressions below:

$\frac{x^2-4x}{x^2-2x-8x}$