The slope of the line that passes through the points (x1, y1) and (x2, y2) is computed as follows:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
From the graph, f(x) passes through the points (0, 4) and (2, 1), then its slope is:
[tex]m=\frac{1-4}{2-0}=-\frac{3}{2}[/tex]
