Answer
$\dfrac{f(a+h)-f(a)}{h}=\dfrac{\dfrac{3}{a+h}-\dfrac{3}{a}}{h}$
Work Step by Step
Using the results of Exercises 45 and 46, then
\begin{array}{l}\require{cancel}
\dfrac{f(a+h)-f(a)}{h}=\dfrac{\dfrac{3}{a+h}-\dfrac{3}{a}}{h}
.\end{array}