## Precalculus (6th Edition)

The given relation defines $y$ as a function of $x$. domain: $(-\infty, 0) \cup (0, +\infty)$ range: $(-\infty, 0) \cup (0, +\infty)$
Solve for $y$ to obtain: $xy = 2 \\\frac{xy}{x} =\frac{2}{x} \\y=\frac{2}{x}$ This means that the given equation is equivalent to $y=\frac{2}{x}$. The equation above will give only one value of $y$ for every value of $x$. This means that each $x$ is paired with only one value of $y$. Thus, the given relation defines $y$ as a function of $x$. Note that in $y=\frac{2}{x}$, the value of $x$ cannot be zero.This means that the domain of the given function is the set of real numbers except $0$. In interval notation, the domain is $(-\infty, 0) \cup (0, +\infty)$. Note that when $2$ is divided by any non-zero number, the quotient will never be zero. Thus, the value of $y$ can be any real number except zero. In interval notation, the range is $(-\infty, 0) \cup (0, +\infty)$.