Respuesta :
a set is NOT a function when there's an x-coordinate that is repeated, so let's check who is who.
[tex]\bf A.\{(\stackrel{re peat}{3}, 1), (-1,1), (1, 1), (\stackrel{re peat}{3}, -1)\}\quad \otimes\\\\ B.\{(-3, 1), (-1, 1), (1, 1), (3, 1)\}\quad \checkmark\\\\ C.\{(-3, 1), (-1, -1), (1, 1), (3, 1)\}\quad \checkmark\\\\ D.\{(-3, 1), (-1, -1), (1, 1), (3, -1)\}\quad \checkmark[/tex]
[tex]\bf A.\{(\stackrel{re peat}{3}, 1), (-1,1), (1, 1), (\stackrel{re peat}{3}, -1)\}\quad \otimes\\\\ B.\{(-3, 1), (-1, 1), (1, 1), (3, 1)\}\quad \checkmark\\\\ C.\{(-3, 1), (-1, -1), (1, 1), (3, 1)\}\quad \checkmark\\\\ D.\{(-3, 1), (-1, -1), (1, 1), (3, -1)\}\quad \checkmark[/tex]
Answer:
a set is NOT a function when there's an x-coordinate that is repeated
