Appendix A - Review - A.1 Algebra Essentials - A.1 Assess Your Understanding - Page A12: 100

$ \displaystyle \frac{1}{x^{3}y}$

Note that: $\displaystyle \frac{x^{-2}y}{xy^{2}}=\frac{x^{-2}}{x}\cdot\frac{y}{y^{2}}\quad$ Apply rule $\displaystyle \quad \frac{a^{m}}{a^{n}}=a^{m-n}$ $=x^{-2-1}y^{1-2}$ $=x^{-3}y^{-1}\quad$. Apply rule $\displaystyle \quad a^{-n}=\frac{1}{a^{n}}$ $=\displaystyle \frac{1}{x^{3}}\cdot\frac{1}{y}$ $=\displaystyle \frac{1}{x^{3}y}$