In this problem, and its graph are given. Use the graph of to determine where is concave down.

Question

In this problem,  and its graph are given. Use the graph of  to determine where  is concave down. ​

Quizplus · Accepted Answer

The graph of the given function has an inflection point at x = 4.5. A function is concave down (or convex up) to the left of an inflection point and concave up (or convex down) to the right of an inflection point. 
Looking at the answer choices, we can see that only choice D has an inflection point to the right of x = 4.5, indicating that the function is concave down at that point. Therefore, the answer is D.

In This Problem, and Its Graph Are Given