Question

If you change the sign of a point’s y-coordinate, how will the location of the point change

Answer 1

Why not experiment?  Plot the point (2,7),  Then change the y-coordinate's sign:  (2,-7).  Plot this new point.  How did the location of (2.7) change when you changed the sign of the y-coordinate (7)?

Answer 2

It will reflect across the x axis