Answer
Domain: All real numbers $x$ such that $x \ne 0$
Range: All real numbers $y$ such that $y \ne 0$
Work Step by Step
$g(x)=\frac{4}{x}$
The denominator of the function must not equal zero, so the domain is:
All real numbers $x$ such that $x \ne 0$
In reciprocal functions, there is a horizontal asymptote, so the range is:
All real numbers $y$ such that $y \ne 0$