Answer
a. $\frac{16}{625}$
b. $\frac{1}{16}$
Work Step by Step
a.
$(\frac{2}{5})^{4}$
$=\frac{2^{4}}{5^{4}}$
$=\frac{2\times2\times2\times2}{5\times5\times5\times5}$
$=\frac{4\times2\times2}{25\times5\times5}$
$=\frac{8\times2}{125\times5}$
$=\frac{16}{625}$
b.
$(-\frac{1}{4})^{2}$
$=\frac{1^{2}}{4^{2}}$
$=\frac{1\times1}{4\times4}$
$=\frac{1}{16}$