Answer
17
Work Step by Step
For t = 6 the instantaneous velocity is $\lim\limits_{b \to 6} \frac{s(b) - s(6)}{b-6}$
$s(b)=b^{2} + 5b + 2$
$s(6) = 68$
The instantaneous rate of change is then: $\lim\limits_{b \to 6} \frac{b^{2} + 5b + 2-68}{b-6}= \lim\limits_{b \to 6} \frac{(b-6)(b+11)}{b-6}=\lim\limits_{b \to 6}(b+11) = 17$
