From My understanding points of inflection are the points where a curve changes direction ( concave up to concave down, concave down to concave up). This only applies to graphs that curve so functions like the Zeus* function would not have a point of inflection. The other functions like f(x)= X is also would not have a point of inflection. Other functions naturally have points of inflections like the polynomial cubic functions.

*reference to the in class project assignment with the parent functions.