#### Answer

Domain: $(-\infty, +\infty)$
Range: $(-\infty, +\infty)$
Refer to the image below for the graph.

#### Work Step by Step

$f(x)=-2x$
The x-intercept can be found by letting f(x)=0.
Here,
$0=-2x$
$0=x$
Hence, 0 is the x-intercept, therefore we plot (0,0).
However, we have already found the y-intercept, too.
We have to find another point on the graph. We let x=1
Here,
$f(x)=-2\times 1$
$f(x)=-2$
Therefore we plot (1, -2).
By connecting these two points by a straight line, we get the graph.
The domain is $(-\infty, \infty)$ as the function will "work" for all real x-values.
(We can see the domain on the graph too. As for every x-value we will find a corresponding point on the graph.)
The range is $(-\infty, \infty)$ as we will get all real y-values after substituting all real x-values in the function.
(We can see the domain on the graph too. As for every y-value we will find a corresponding point on the graph.)