Simplify first, then substitute for evaluation, analyze: remove brackets first, then merge similar items, and then substitute for data evaluation;

In polynomials, terms with the same letters and the same degree are similar terms. Merging similar items is to use the multiplication and distribution law to add the coefficients of similar items as new coefficients, and the index of letters remains unchanged.

First deformation, then overall substitution, analysis: first remove brackets, merge similar terms, then compare the simplified algebraic expression with the given equation, and solve it through the idea of overall substitution.

Special conditions are substituted for evaluation and analysis: the algebraic expression is simplified by merging similar terms, and then the values of x and y are obtained by using the "0+0=0" model, and then substituted for the simplified algebraic expression for evaluation.

Evaluation and analysis of total addition and subtraction: there is a binary quadratic equation in the topic, which is unrealistic to solve directly. Observe the characteristics of algebraic expressions. It can be found that the coefficient in front of the x square term is 2, so the first formula can be expanded twice; The coefficient in front of the y square term is -3. You can triple the second formula and then add the two formulas.

When solving the problem of algebraic expression simplification, we should pay attention to the format problem. Generally, it is necessary to simplify before evaluating, that is, do not directly substitute the data given in the topic, which not only requires a lot of calculation, but also is easy to make mistakes and has insufficient format.

Algebraic simplification is a major focus of junior high school mathematics, and its main contents include algebraic addition, subtraction, multiplication and division, power operation, variance formula and complete square formula.

Simplified evaluation: As the name implies, it is to dissolve a complex formula into the simplest form and then evaluate it according to the known conditions.