Answer
See graph and explanations.
Work Step by Step
1. Graph $y=3^x$ using test points $x=-2,-1,0,1,2...$ as shown in the figure (red curve)
2. Reflect the curve around the x-axis to obtain $f(x)=-3^x$ (blue curve)
3. We can find the domain of $f(x)$ as $(-\infty,\infty)$ and range as $(-\infty,0)$
