Chapter 1 - Functions and Limits - 1.8 Continuity - 1.8 Exercises - Page 91: 6

The functions must have discountinous at $x=-1 $ and $x=4$ which is shown in following graph.

As we know that the graph of the function $y=f(x)$ must have discountinuities at $x=-1$ and $x=4$. It shows that $\lim\limits_{a \to -1^-}f(x)=f(-1)$ and $\lim\limits_{x \to 4^+}f(x)=f(4)$ which is represented by the following graph;