In the xy-plane, the origin O is the midpoint of line segment PQ. If the coordinates of P are (r,s), what are the coordinates of Q ?

A) (r,s)

B) (s,-r)

C) (-s,-r)

D) (-r,s)

E) (-r,-s)

Solution: Greg choose (2,3) as P and so the Q would be (-2,-3), hence choosing E) (-r, -s) as the answer.

But suppose we pick the point (5,0) as P then Q would be (-5,0). With this could D) (-r, s) be the answer too ?