$[16]2.$ Let $F(x)=\frac{3x-0\mathrm{.}5x^2}{x^2-8x+12}.$

a$)$ Evaluate $\underset{x}{lim}F(x)$ and $\underset{x-}{lim}F(x).$

b$)$ At which $x$ values is $F$ discontinuous?

c$)$ At each $x$ value a where $F$ is discontinuous, find $\underset{x{a}^{-}}{lim}F(x)$ and $\underset{x{a}^{+}}{lim}F(x).$

d$)$ Give the equations of all horizontal asymptotes for $F$ :

Give the equations of all vertical asymptotes for $F$ :