As the function is concave from 0 to 9, this means that near the extremes of this interval it are larger. Thefore the numbers numbers near the extreme will have the higher values:
[tex]\begin{gathered} \frac{f(6)-f(4)}{6-4} \\ \frac{f(8)-f(6)}{8-6} \end{gathered}[/tex]Since f(8) and f(6) are closer to the extreme it means that those are the larger values.
