Answer
domain $(-\infty,\infty)$, range $(-4,\infty)$
See graph.
Work Step by Step
To graph function $f(x)=2^x-4$, start from $y=2^x$, shift the curve 4 units down.
For $f(x)$, we have domain $(-\infty,\infty)$, range $(-4,\infty)$
See graph.