Answer
domain $(-\infty,\infty)$, range $(0,\infty)$
See graph.
Work Step by Step
To graph function $f(x)=2^{-x}=(\frac{1}{2})^x$, start from $y=2^x$, reflect across the y-axis.
For $f(x)$, we have domain $(-\infty,\infty)$, range $(0,\infty)$
See graph.