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**Unformatted text preview: **lthough it is quite pleasing to the eye, it isn’t the most portable way to describe
R. The list (or roster) method of describing R simply lists all of the points which belong to R.
Hence, we write: R = {(−2, 1), (4, 3), (0, −3)}.1 The roster method can be extended to describe
inﬁnitely many points, as the next example illustrates.
Example 1.2.1. Graph the following relations.
1. A = {(0, 0), (−3, 1), (4, 2), (−3, 2)}
2. HLS1 = {(x, 3) : −2 ≤ x ≤ 4}
3. HLS2 = {(x, 3) : −2 ≤ x < 4}
4. V = {(3, y ) : y is a real number}
1 We use ‘set braces’ {} to indicate that the points in the list all belong to the same set, in this case, R. 1.2 Relations 15 Solution. 1. To graph A, we simply plot all of the points which belong to A, as shown below on the left. 2. Don’t let the notation in this part fool you. The name of this relation is HLS1 , just like the
name of the relation in part 1 was R. The letters and numbers are just part of its name, just
like the numbers and letters...

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