數學題,中一的

1.The x-coordinate of (-1,9) is _________.

2.The y-coordinate of (8,7) is _________.

3.If P is a point on the x-axis,then the y-coordinate of P is _________.

4.The coordinate of the origin = _________.

5.The distance between the points (12,5) and (18,5) is _________.

6.The distance between the points (x,y) and (-x,y) is _________.