1 and one-dimensional linear equations all contain only one unknown, and the formulas containing the unknown are all algebraic expressions, and the degree of the unknown is 1.

2. Binary linear equations all contain two unknowns, and the number of unknowns is 1.

3. The basic methods for solving binary linear equations are substitution elimination method and addition and subtraction elimination method. The core of the two methods is "elimination", which transforms binary linear equations into univariate linear equations, which embodies the reduction idea of "simplifying the complex" and "turning the unknown into the known". The specific methods of solving equations should be chosen flexibly according to their characteristics.

4. When solving the equation, both sides of the equation are multiplied by the same number that is not equal to 0, so the coefficient in the equation has no score. This deformation is often called "naming".