Answer
$(0,1), (2,-1)$ and $(-2,3)$ are located on the graph.
Work Step by Step
$\textbf{To determine whether a point is on a line,}$
$\textbf{simply plug the points back into the equation}$.
When we plug in $(0,1), (2,-1)$ and $(-2,3)$ into the equation of $x^2+2xy+y^2=1$ as $x$ and $y$ respectively, the equation works out, which indicates that the points are located on the graph.