Answer
a) These expressions are not equal
b) There is a difference between these two expressions
Work Step by Step
a) We have ($\frac{2}{3}$)$^{-2}$= $\frac{1}{(\frac{2}{3})^{2}}$= $\frac{1}{(\frac{4}{9})}$ = $\frac{9}{4}$
b) (-5)$^{4}$= (-5) $\times$ (-5) $\times$ (-5) $\times$(-5) = 25 $\times$ 25 = 625
However, -5$^{4}$= -(5$^{4}$) = -625
