Final answer:
To determine if a function is increasing, decreasing, or constant, one often looks at the slope of the graph, rather than using numerical values or specific calculation outputs from the function's formula.
Step-by-step explanation:
When determining if a function is increasing, decreasing, or constant, you do not typically use numerical values or specific calculations of the function's output. Instead, you consider the general behavior of the function over intervals on its domain. To determine the behavior of a function, you look at the slope of the function, or the rate of change, on a graph. If the slope is positive in an interval, the function is increasing. When the slope is negative, the function is decreasing.
If there is no slope (the line is horizontal), the function is constant on that interval. While exact numerical values from the function's formula can confirm these behaviors, they are generally not used to define whether a function is increasing, decreasing, or constant.