Answer
$[0, 4]$
Refer to the graph below.
Work Step by Step
The given inequality is
$\Rightarrow 0\leq x \leq 4$
Left and right bracket indicates that $0$ and $4$ are part of the graph.
Thus, the closed interval is $[0,4]$.
To graph, use lef tand right brackets at $0$ and $4$ respectively, then shade the region inside.
Refer to the graph below.
