Increasing and Decreasing Functions

A function is increasing if its graph rises from left to right. Observe that the trend is increasing for lines with positive slopes. Note also that a function is increasing if for any points $\left(x_1,y_1\right)$ and $\left(x_2,y_2\right)$ in the interval, $y_1<y_2$ whenever $x_1<x_2.$ The graph of a line shown in the figure below is an example of an increasing linear function.