Answer
a) blue graph is a one-to-one function
b) red graph is the graph of the inverse function
Work Step by Step
A horizontal line drawn anywhere on the plane will intersect the given graph at only $1$ point. Hence, the given graph is a graph of a one-to-one function.
Interchanging the $x$ and $y$ coordinates of the given points, $
(-1,5),(2,-1)
$ results to the points
\begin{align*}\require{cancel}
(5,-1),(-1,2)
.\end{align*}
By connecting the new points above, then the graph of the inverse function is determined (red graph).
