Answer:
x = -0.5
Step-by-step explanation:
I have marked on the graph the values of ƒ(x) that correspond to the different x-values.
At x = -2.5, ƒ(x) is decreasing, concave up, and > 0.
At x = -1.5, ƒ(x) is decreasing, concave down, and < 0.
At x = -0.5, ƒ(x) is increasing, concave up, and < 0.
At x = 0.5, ƒ(x) is increasing, concave up, and > 0.
At x = 2.5, ƒ(x) is decreasing, concave up, and > 0.
The only point for which ƒ(x) is simultaneously increasing, concave up, and less than zero is x = -0.5.