Which ordered pair is not a solution of 1x) = 2x+9?
(7,23)
(3, 14)
(2, 13)
(0.9)

Answer:
Just plug the coordinates into the equation; f(x) will be the y coordinate whereas x will be the x coordinate
In this case the answer is (3,14)
Proof: 14=2(3)+9
14=6+9
14≠15