The notion of an asymptote can be extended to include curves as well as lines. Specifically, we say that curves $y=f(x)$ and $y=g(x)$ are asymptotic as $x \rightarrow+\infty$ provided
$$
\lim _{x \rightarrow+\infty}[f(x)-g(x)]=0
$$
In these exercises, determine a simpler function $g(x)$ such that $y=f(x)$ is asymptotic to $y=g(x)$ as $x \rightarrow+\infty$ or $x \rightarrow-\infty$ Use a graphing utility to generate the graphs of $y=f(x)$ and $y=g(x)$ and identify all vertical asymptotes.
$$
f(x)=\frac{-x^{3}+3 x^{2}+x-1}{x-3}
$$