#### Answer

Concave upward on
$$
(-\infty, -1) \text{ and } (8,\infty).
$$
Concave downward on
$$
(-1, 8).
$$
Inflection points at
$$
(-1, 7) \text{ and } (8,6).
$$

#### Work Step by Step

Since the graph of the function lies above its tangent line at each point of $(-\infty, -1)$ and $(8,\infty)$
So, concave upward on
$$
(-\infty, -1) \text{ and } (8,\infty).
$$
Since the graph of the function lies below its tangent line at each point of $(-1, 8)$ .
So, concave downward on
$$
(-1, 8).
$$
Since a point where a graph changes concavity is $(-1,7)$ and $(8,6)$
So, Inflection points at
$$
(-1, 7) \text{ and } (8,6).
$$