Today's math teacher taught cross multiplication will not, I am confused, who rescue save me how to solve? To simple point of the solution.

Is this from high school? Multiplication of Crosses - The method of factoring a quadratic polynomial by decomposing the coefficients with the help of drawing crosses is called multiplication of crosses.

Cross multiplication is a common method of factoring quadratic trinomials, it is the first quadratic trinomial of the quadratic coefficients a and the constant term c are decomposed into the product of the two factors (there are several different ways to divide)

Then according to the diagonal cross multiply, and then add, if there is , then there is , otherwise, you need to exchange the position of the second try again, and if it still does not work, and then change the other set of the same method until you find the right one. If it still doesn't work, then change another group and test with the same method until you find the right one.

. General steps of factorization

(1) If the polynomials have a common factor, the common factor should be extracted first;

(2) If the polynomials do not have a common factor, consider whether they can be factored by the formula method;

(3) For the factorization of quadratic polynomials, the cross multiplication method can be considered;

(4) For polynomials of more than three terms, generally the cross multiplication method should be considered;

(5) For polynomials of more than three terms, the cross multiplication method can be considered. polynomials, the group factorization method should generally be considered.

When factoring, it is necessary to combine the form and characteristics of the topic to determine which method to use. These four methods are related to each other, not a type of polynomials can only use one method to factorize, we must learn to analyze specific problems.

When we do the problem, we can refer to the following mnemonic:

First extract the common factor, and then consider using the formula;

Cross multiplication try, divided into groups to be appropriate;

Four ways to try again and again, and finally must be a multiplicative formula.