## Calculus 10th Edition

The graph in the first and second quadrants is $f(x)$ while the one in the first and third quadrants is $f'(x).$
When $f(x)$is decreasing $f'(x)$ has to be negative while when $f(x)$ is increasing $f'(x)$ has to be positive; Looking at the graphs we realize that when the graph in the first and second quadrants is decreasing, the other graph is negative while the opposite is not true. Hence, the graph in the first and second quadrants is $f(x)$ while the one in the first and third quadrants is $f'(x).$