1.If X and Y are two points on a number line, then the distance between them is represented by . 2.The segment addition postulate can only be used for the points that are .

Answers:

Either |x-y| or |y-x|collinear

Explanations:

To find the distance, we subtract the two values. Absolute value is used to ensure the result isn't negative. Notice how something like 5-2 = 3 and 2-5 = -3, so we can say |5-2| = 3 and |2-5| = 3 so we don't get a negative distance. In general for x and y, the distance between them is either |x-y| or |y-x| as they represent the same distance. So on a number line, |x-y| = |y-x|.The segment addition postulate is the idea where we can break up a large segment into smaller pieces. We can then glue those pieces back together to get the larger segment again. This only works if all points are on the same line. If all points are on the same straight line, then we consider them to be collinear.