Graphs that bend upwards or downwards are called concave functions. A function that has a positive slope or increases, is called a “concave upwards” function which means the rate of change is increasing. On the other hand, a downward concave function is when the rate of change decreases. It has a negative slope or downward curve. The first graph concave upwards while the second graph concave downwards. What else do you know about concave functions?