4. For the graph of this rational function: $y=\frac{x^{2}-7 x+12}{x-3}$ Determine any non-permissible values of $x$, holes, and/or-asymptotes then sketch the graph.

Step 1 ：Factor the numerator: $y=\frac{(x-3)(x-4)}{x-3}$

Step 2 ：Since there is a hole at $x=3$, the factors $(x-3)$ cancel out: $y=x-4$

Step 3 ：The non-permissible value of $x$ is $x=3$

Step 4 ：There is a hole at $x=3$

Step 5 ：There are no vertical asymptotes since the factors cancel out

Step 6 ：Sketch the graph of $y=x-4$ with a hole at $x=3$