1 and how much are three coats?

380×3= 1 140 (yuan) Answer: Three coats are needed 1 140 yuan.

2. How much are three pairs of trousers?

249×3=747 (yuan) A: Three pairs of trousers need 747 yuan.

How much does it cost to buy a suit?

380+249=629 (yuan) A: It costs 629 yuan to buy a suit.

Methods to solve mathematical problems:

1, matching method.

The so-called formula is to change some items of an analytical formula into the sum of positive integer powers of one or more polynomials by using the method of constant deformation. The method of solving mathematical problems with formulas is called matching method. Among them, the most common method is to make it completely flat.

Matching method is an important method of constant deformation in mathematics. It is widely used in factorization, simplifying roots, solving equations, proving equality and inequality, finding extreme values of functions and analytical expressions.

2. Factorization method.

Factorization is to transform a polynomial into the product of several algebraic expressions. Factorization is the basis of identity deformation. As a powerful mathematical tool and method, it plays an important role in solving algebra, geometry and trigonometry problems.

There are many methods of factorization, such as extracting common factors, formulas, grouping decomposition, cross multiplication and so on. Middle school textbooks also introduce the use of decomposition and addition, root decomposition, exchange elements, undetermined coefficients and so on.

3. Alternative methods.

Method of substitution is a very important and widely used method to solve problems in mathematics. We usually refer to unknowns or variables as elements. The so-called method of substitution is to replace a part of the original formula with new variables in a complicated mathematical formula, thus simplifying it and making the problem easy to solve.

4. Discriminant method and Vieta theorem.

The root of the unary quadratic equation a2+b+c=0(a, B, C belongs to R, A is not equal to 0), and s=b2-4ac is not only used to determine the properties of the root, but also widely used in algebraic deformation, solving equations (groups), solving inequalities, studying functions and even geometric and trigonometric operations as a problem-solving method.