Answer
a) $\sqrt{a+h}-\sqrt a$
b) $\dfrac{1}{h}(\sqrt{h+a}-\sqrt a)$
Work Step by Step
a) Apply the rule such as: $f(b)-f(a)$ where $a \leq b$
Thus, the net change is given as:
$f(b)-f(a)=f(a+h)-f(h)$
This gives:
$f(a+h)-f(h)=\sqrt{a+h}-\sqrt a$
b) Apply the rule such as: $f(b)-f(a)$ where $a \leq by$
Thus, the average rate is given as:
$\dfrac{f(b)-f(a)}{b-a}=\dfrac{f(a+h)-f(a)}{(a+h)-a}$
This gives:
$\dfrac{2/a+h-2/a}{a+h-a}=\dfrac{1}{h}(\sqrt{h+a}-\sqrt a)$
