Definition: 1. Inequalities must be satisfied, that is, the starting point of your problem solving is to make the inequality you solve always hold and will not conflict with the meaning of the problem;

On the premise of satisfying point 1, the range of variables in inequality is obtained. In other words, any number in the range satisfies the inequality. The value of a variable is not a fixed value, but a set consisting of several or more unfixed values or regional ranges, that is, its solution set.

The solution set is an interval, such as x+2 >; The solution set of 1 is X >；; - 1