## Precalculus (6th Edition)

$\dfrac{2}{3}r^3$
RECALL: (1) $a^{-m} = \dfrac{1}{a^m}$ (2) $\dfrac{a^m}{a^n} = a^{m-n}$ (3) $\left(\dfrac{a}{b}\right)^m=\dfrac{a^m}{b^m}$ (4) $(ab)^m = a^mb^m$ Divide the coefficients together by canceling common factors, then use rule (2) above to simplify the variable to obtain: $\require{cancel}=\dfrac{\cancel{4}2}{\cancel{6}3}{r^{-3-(-6)}} \\=\dfrac{2}{3}r^{-3+6} \\=\dfrac{2}{3}r^3$