In order to calculate the rate of change, we can use the following derivatives:
[tex]\begin{gathered} u=\frac{1}{a+x} \\ \frac{du}{dx}=-\frac{1}{(a+x)^2} \\ \\ u=\frac{1}{a-x} \\ \frac{du}{dx}=\frac{1}{(a-x)^2} \end{gathered}[/tex]
So, calculating the rate of change in each case, we have:
a)
[tex]\begin{gathered} F=\frac{130600}{321-x} \\ \frac{dF}{dx}=\frac{130600}{(321-x)^2}=\frac{130600}{(321-25)^2}=\frac{130600}{296^2}=\frac{130600}{87616}=1.491 \end{gathered}[/tex]
b)
[tex]\begin{gathered} F=\frac{130600}{321+x} \\ \frac{dF}{dx}=-\frac{130600}{(321+x)^2}=-\frac{130600}{(321+25)^2}=-\frac{130600}{346^2}=-\frac{130600}{119716}=-1.091 \end{gathered}[/tex]
