## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$\dfrac{25t^{6}}{r^{8}}$
Using the laws of exponents, the given expression, $(5r^{-4}t^3)^2$, is equivalent to \begin{array}{l} 5^{2}r^{-4(2)}t^{3(2)} \\\\= 25r^{-8}t^{6} \\\\= \dfrac{25t^{6}}{r^{8}} .\end{array}