Answer
$$\left( {\bf{a}} \right)2.9690,\,\,\,\left( {\bf{b}} \right)0.0341$$
Work Step by Step
$$\eqalign{
& \left( {\bf{a}} \right){2^{1.57}},\,\,\,\,\,\left( {\bf{b}} \right){5^{ - 2.1}} \cr
& {\text{Using a calculating utility and rounding the answer to four decimal places,}} \cr
& {\text{we obtain }} \cr
& {2^{1.57}} \approx 2.9690 \cr
& {5^{ - 2.1}} \approx 0.0341 \cr} $$