The inflection points of a function are the points at which the function changes its curvature.
It is evident from the graph that each square of the grid has a side 1 unit.
Now, it can be observed that the function is concave down before x = -1, then concave up till x=4, and again concave down afterwards.
It follows that the function changes its concavity at points x = -1, and x = 4.
Therefore, it can be concluded that the function has points of inflection at,
