The simple introduction of the cross decomposition method by cross multiplication is that the multiplication on the left side of the cross is equal to the quadratic term, the multiplication on the right side is equal to the constant term, and the cross multiplication is equal to the coefficient of the linear term. In fact, it is factorization by multiplication formula operation.
Cross multiplication is a method of factorization. For quadratic form, it is more convenient to integrate the coefficients. Of course, the quadratic coefficient is preferably 1. It's easy to think that constant terms are integers, but fractions can also be used.
The usage of cross multiplication and the usage of formula cross multiplication: the left multiplication of the cross is equal to the quadratic term coefficient, the right multiplication is equal to the constant term, and the cross multiplication and addition are equal to the linear term coefficient.
In fact, it is to use the multiplication formula (x+a)(x+b)=x? +(a+b)x+ab for factorization.
Method of cross multiplication: Formula: Divide by quadratic term, divide by constant term, cross multiply and sum to get linear term.
The above is the information about cross multiplication for your reference.