1. Equation: An equation with an unknown number is called an equation.

Note: (1) equation is an equation and contains unknowns, both of which are indispensable.

(2) The formula and calculation method are different. Arithmetic formula is a formula, which consists of operator number and known number, and it represents unknown number. An equation is an equation, and the unknown in the equation can participate in the operation. Only when the unknown is a specific numerical value can the equation be established.

2. Solution of the equation: The value of the unknown that makes the left and right sides of the equation equal is called the solution of the equation.

Second, solve the equation.

1. Solving equations: The process of solving equations is called solving equations.

2. Steps to solve the equation:

(1) denominator;

(2) remove the brackets;

(3) moving items;

(4) merging similar projects;

(5) The coefficient is1;

(6) Test the root.

Third, solve application problems with column equations.

1. The significance of solving application problems by using column equations

By solving the application problem with equation, the unknown quantity of the application problem can be obtained, which can make the meaning of the problem more clear and solve the problem.

2. List the steps of solving application problems with equations.

(1) Find out the meaning of the problem and determine the unknown number, which is represented by X;

(2) Find out the equal relationship between the quantities in the questions;

(3) column equation, solving equation;

(4) check or check, and write the answer.

3. The method of solving application problems with column equations

(1) synthesis method: first, the known number (quantity) and the unknown number (quantity) in the application problem are listed as related algebraic expressions, and then they are solved.

The equivalent relationship between them, and then list the equations. This is a thinking process from part to whole, and its thinking direction is from known to unknown.

(2) Analysis method: First find out the equivalence relation, then according to the need of establishing equivalence relation, list the known number (quantity) and unknown number (quantity) in the application problem into related algebraic expressions, and then list the equations. This is a thinking process from the whole to the part, and its thinking direction is from unknown to known.