Chapter R - Algebra Reference - R.6 Exponents - R.6 Exercises - Page R-25: 25

$\displaystyle \frac{xy}{y-x}$

$(x^{-1}-y^{-1})^{-1}$=.........$\displaystyle \frac{1}{a^{n}}=a^{-n}$ $=(\displaystyle \frac{1}{x}-\frac{1}{y})^{-1}$=........common denominator =$xy$ $=(\displaystyle \frac{y}{xy}-\frac{x}{xy})^{-1}$ $=(\displaystyle \frac{y-x}{xy})^{-1}$=.........$\displaystyle \frac{1}{a^{n}}=a^{-n}$ $=(\displaystyle \frac{xy}{y-x})^{1}$ $=\displaystyle \frac{xy}{y-x}$