X is a letter in the word dictionary We read it as A is the set of all x such that x is a letter in the word dictionary Examples. To combine two intervals using inequality notation or set-builder notation we use the word or As we saw in earlier examples we use the union symbol to combine two unconnected intervals. A x.
X is a whole number and x 20 Example 5.
2 U 3 We used a U to mean Union the joining together of two sets. Thus there is a variable on the left of the separator and a rule on the right of it. Set-Builder Notation and Interval Notation. X is a positive even number Example 4.