Plug in the points on the graph into your equations and see if they work out.
For example, take the point (2, 3) and see if it works in the first equation y^2 +1 = -2x + 1.
(3)^2 +1 = -2(2) +1
10 =/= -3
That didn't work out, did it?
If you continue to do the same for all the equations, you will eventually find that the only equation that works for all points on the graph is choice 2.
