## Discrete Mathematics with Applications 4th Edition

In ordered pairs, the order in which the elements appear matters, unlike in normal sets. Recall that $(a,b)=(c,d)$ if and only if $a=b$ and $c=d$. In part (d), for example, $\frac{-2}{-4}=\frac{3}{6}=\frac{1}{2}$ and $(-2)^{3}=(-2)\times (-2)\times (-2)=-8$.