Answer
$(-3,2)$ and $(0,1)$ are located on the graph.
$(2,1)$ is not located on the graph.
Work Step by Step
$\textbf{To determine whether a point is on a line, simply plug the points back into the equation}$.
When we plug in $(-3,2)$ and $(0,1)$ into the equation of $y=\sqrt{1-x}$ as $x$ and $y$ respectively, the equation works out, which indicates that the points are located on the graph.
But when we plug in $(2,1)$ into the equation, the equation is not work out, which indicates that the point is not located on the graph.