{All real numbers greater than-1 and less than 3}. The description of a set is to use a brace and then express the language that conforms to the meaning of the question. There are many representations of sets, and inequality methods can also be used. {Xi- I<x & lt3}. The set can also be operated. Set problem is an important content of senior one mathematics. The relationship between the elements in the set and the set belongs to the relationship.

You can omit the range when x ∈ r, otherwise you need to fill in the range. The form of descriptive representation set is {XL? X has an attribute} where X is the representative element of a set. If this set is a set of numbers, then the value range of X needs to be limited. For example, the {x ∈ NL-2 ≤ x ≤ 2} set contains only three elements 0, 1, 2. If X∈Z, the set contains five elements -2,-1, o, 1, 2. If it is not in the range, it means all real numbers greater than or equal to -2 and less than or equal to 2.

Description is one of the representation methods of mathematics set in senior one, which is suitable for infinite sets. Of course, finite sets can also be described, but it is more troublesome to write with descriptions. The format of describing a set is to write a brace, write the letter representing the element on the left side of the brace, then draw a vertical line, and then write down the conditions that the element meets.