For a long time, mathematical operation is a very difficult topic for candidates in the exam, and these topics can effectively open the scores between candidates, so it should be paid attention to. For this kind of questions, as long as candidates can carefully analyze the equivalence relationship in the stem, they can solve it with the help of the general method in mathematics-equation method.

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1. Definition of equation: Equation refers to an equation with unknown numbers. Equation method is to put the unknown quantity and the known quantity in the same position when solving the problem, that is, treat the unknown quantity as the known quantity, then list the corresponding equations according to the equivalence relationship between the known quantity and the unknown quantity in the problem, and finally find out what the unknown quantity is.

Second, the core of the equation:

1. Set unknowns: the number of unknowns should be as small as possible, and fractions and decimals should be avoided. ① Set basic unknowns; Basic unknowns refer to other unknowns related to them. (2) There is a proportional relationship, which is set as proportional relationship.

2. Establish equivalence relation: ① According to the key words in the stem, such as: greater than/less than ..., one * * *, several times ... ② Common formulas, such as: total price = unit price × quantity, etc.

3. Steps to solve problems with column equations

(1) Review the topic and find out the meaning of the topic. That is, comprehensively analyze the relationship between known number and known number, known number and unknown number, especially clarify some concepts and terms involved, such as direction, opposite direction, increase to and increase.

(2) introduce the unknown. X is used to indicate the required quantity or related unknown quantity. The application problems encountered in primary school are not very complicated, and generally only need to set the required numbers directly as unknown;

(3) Find out the equal relationship between quantity and quantity in the application problem, and list the equations;

(4) solving the equation and finding the value of the unknown quantity;

(5) Test and write the answer. When testing, we should first substitute the unknown values into the original equation to test whether the solution of the equation is correct; The second is to check whether the unknown values are consistent with the meaning of the question, discard those that are not, and keep the solutions that are consistent with the meaning of the question.