Answer
See the graph
Work Step by Step
We are given: $y=-3x^2$
Make a table of values.
$x=-2 \rightarrow y=-12$
$x=-1 \rightarrow y=-3$
$x=0 \rightarrow y=0$
$x=1 \rightarrow y=-3$
$x=2 \rightarrow y=-12$
The domain is all real numbers. The range is $y \leq 0$.