Generally speaking, linear equation is the basis of linear inequality, because solving linear inequality requires many theorems of linear equation, such as adding, subtracting, multiplying and dividing a formula on both sides of a symbol at the same time, and the change of numerical relationship between them. A linear function needs a linear equation and a linear inequality. For example, the linear function y=2x, and when x= 1, the linear equation y=2* 1 is solved. Of course, the problem will be much more difficult than this. When I ask you what the value range of y>0 and X is, I can solve 2x >；; 0 is a linear inequality.