How do you use cross multiplication? How to multiply the crosses

It's simple. It seems complicated, but in fact I talk a lot of nonsense. Since you said you wouldn't, I wanted to go into more detail.

I'll start by saying that if you really want to figure it out, then read on. This is all slowly typed out by me, you really want to learn you can definitely understand, if your attitude is not very good, I believe you can't understand what I said. Then there is nothing I can do about it.

w=Let's say. x^2-5x+6=0.

Let's start with its quadratic coefficients and constants. For example, the coefficient of the quadratic term is 1(I'll talk about the quadratic coefficient of 1 first), so you draw a 2*2 square first (of course, I'm just when you don't know how to teach you to draw a square) The two squares in the left column of the square are for the quadratic coefficients, and the two squares on the right are for constants.

Since the quadratic coefficient is 1, the left ones are 1 and 1 respectivelyYou need to make sure that the product of the two numbers in the left and right squares is the number corresponding to the square (e.g. 1*1=1, so you can use 1 and 1). So the 6 on the right.

Only 2*3=6 or -2*-3=6 or 1*6=6 or -1*-6=6It's time to try it. You put them in the compartment separately.

Then the diagonal diagonal two of the 4 squares are multiplied by each other. From this we get two numbers. Let's talk about adding these two numbers.

If the resulting number is equal to the coefficient term of the primary term in the original equation (e.g. the coefficient of the primary term in this problem is 5). Then you will find that if you substitute 1 and 6, then you get 1 and 6 firstAdds up = not equal to -5, so not 1 and 6

If it is -1 and -6The resulting numbers are -1 and -6Adds up = -7

Nor is it equal to -5If it's 2 and 3The resulting numbers 2 and 3 add up to = 5 and do not equal -5.

Finally, substitute -2 and -3Get -2 and -3Adds up =-5

Then there you have it. You can write (x-2)(x-3)=0.Then you can get x=2 or 3

This is a quadratic term with a coefficient of 1. So what about not 1? Actually, it's the same thing.

The quadratic coefficient that is not 1 is also disassembled. Also substituted in the grid. Then multiply diagonally diagonally to get the two numbers.

Then add it up to see if it's equal to the one-time term coefficient. It's as simple as that. Study hard.

Actually, it's really not that hard.

The method of cross multiplication is simply as follows: the left side of the cross is equal to the quadratic term coefficient, the right side is equal to the constant term, and the cross multiplication and addition are equal to the primary term coefficient.

Cross multiplication can factor certain quadratic trinomials. The key to this method is to decompose the quadratic term coefficient a into the product of the two cross multiplication factors a1 and a2, decompose the constant term c into the product of the two factors c1 and c2 by c2, and make a1c2+a2c1 exactly a term b, then it can be directly written as the result: ax 2 + bx + c = (a1x + c1) (a2x + c2), when using this method to decompose the factor, we should pay attention to observe, try, and realize that it is essentially the inverse process of binomial multiplication.

When the first coefficient is not 1, it often takes several tests, and it is important to pay attention to the symbols of each coefficient. Basic formula: x 2 + (p + q) + pq = ( + p ( q) The so-called cross multiplication method is to use the inverse operation of the multiplication formula (x+a)(x+b)=x 2+(a+b)x+ab to factorize.

The multiplication of the cross is the multiplication of the cross.

1. The method of cross multiplication: the left side of the cross is equal to the quadratic term coefficient, the right side is equal to the constant term, and the cross multiplication and then the addition is equal to the primary term coefficient.

2. The usefulness of cross multiplication: (1) Use cross multiplication to decompose factors. (2) Use cross multiplication to solve a quadratic equation.

3. Advantages of cross multiplication: the speed of solving problems by cross multiplication is relatively fast, which can save time, and the amount of calculation is not large, and it is not easy to make mistakes.

4. Defects of cross multiplication: 1. Some problems are relatively simple to solve by cross multiplication, but not every problem is simple to solve by cross multiplication. 2. Cross multiplication is only applicable to quadratic trinomial type problems. 3. Cross multiplication is more difficult to learn.

Since there is no square symbol in the computer, first we will set the symbol - this symbol represents the quadratic " ".

Let's take the formula "x -5x + 4 = 0".

First of all, we can remove the "x" and "4", "x" can be split into two "x", and "4" can be split into "-4" and "-1". First, let's look at the exploded view: 1) x

4.\x-1

2）x-4./x-1

3）x─4x─

1 (Sorry, that.)"."It's meant to align with where it's supposed to be. )

Second, here's an explanation of the three diagrams:

Step 1: Multiply the "x" in "1)" by "-4".

Step 2: Multiply the "x" in "2)" by "-1".

Step three: 3) "Medium, add "x".

4" vs. "x

1" is written in the same parentheses as (x-4) (x-1).

Thirdly, there is the general step of multiplication with crosses:

1.First, the quadratic formula (i.e., the quadratic unknown) is decomposed into two quadratic formulas, and the product of the two quadratic equations should be equal to the original quadratic formula. That is, the product of "x" and "x" above is "x".

2.The constant term is then decomposed into two constant terms, and the product of the two constant terms should be equal to the original constant term. That is, the product of "-4" and "-1" above is "4".

3.Cross-multiplication is the "1)" and "2)" in the figure above. The two numbers "-x" and "-4x" multiplied by cross-multiplication are added to a one-time formula, i.e., (-x) + (4x) = -5x.

4.As long as the above three conditions are true, you can move on to the next step. Horizontally, as in the direction of "3)", replace "x."

4" vs. "x

1" is written in the same parentheses as (x-4) (x-1). Add the equal sign and write it as (x-4)(x-1)=0.

Finally, pay attention to the conditions:

1> Pay attention to the plus and minus signs.

2> The original equals must be equal to 0 after the equal sign. That is, the form of the formula is "ax +bx+c=0" (a, b, and c in the formula are constants).

3> When the formula is "ax +bx+c=d" (a, b, c, d are all constants), you should move "d" to the left of the equal sign, that is, you must find a way to make the right side of the equal sign "0".

I hope my answer satisfies you, and cross multiplication is something that can be memorized and used flexibly, not something that can be memorized by rote, so I hope you work hard!

The multiplication of the left side of the cross is equal to the coefficient of the quadratic term, the multiplication of the right side is equal to the constant term, and the cross multiplication of the empty hail and the addition of the equal term are earlier than the coefficient of the primary term, such as 2x 2-7x+3 2 1 2 2 1, 3=(-3) (1)=(1) (3), because 2 (3)+1 (-1)=-7 so 2x 2-7x+3=(x-3)(2x-1)

For example, the common valency of the element Pb is , and its average valence state at Pb3O4 is 8 3, and the proportion of atoms in the compound is found.

Do this with cross multiplication: 2 with a valency of 2 has 4 8 3 =4 34 and 4 with a valency of 4 has 8 3 2 =2 3

Then the valency of valency 2 is = 4 3 2 3 = 2 1