I don t understand the math problems, the math problems... Please teach the Great God. Haven t under

Solution: There are x people in total.

9x-5=8x+2

9x-8x=5+2

x=7Please, give me the best.

But... Why is there four classes at the beginning of this question, and then it becomes 2 classes at the end? . .

Solution: If there are x people in the first (4) class of junior high school, then:

9x-5=8x+2

Solution: x=7

Therefore, there are 7 students in the first (4th) class.

You ask if the "(2)" class of the first year of junior high school is wrong?? I started with class (4).

There are x people in the group, and the racket costs y yuan.

then there is y=9x-5

y=8x+2

That is, 9x-5=8x+2

Getting x=7 can be done with unknown numbers.

Here's a quick idea:

If each person pays 9 yuan, it is 5 yuan, and if each person pays 8 yuan, then there is still a shortage of 2 yuan, which means that the total amount of money paid 9 yuan per person is more than the total amount of money paid if each person pays 8 yuan: (5 + 2 = 7 yuan).

This is because each person overpaid: 9-8 = 1 yuan.

The total number of people is: 7 1 = 7 people.

If the question is correct, then I don't know what the relationship between Class 2 and Class 4 is.

If it's just the wrong class number.

If the number of people is x, then 9x-5=8x+2

Calculate x=7

Suppose there are x people who need a total of y yuan, then we get the system of equations 9x-5=y 8x+2=y, and the solution gives x=7 y=58

So there are seven people who have to pay $58.

Let the distance between ab be x, and the first encounter takes t, then the velocity of A is 1000 t, and the velocity of B is (x-1000) t

According to the conditions of the third encounter: (3x-200) (1000 t) = (2x-200) [(x-1000) t].

Solution: x = 1600 meters.

x²+y²=x²+2xy+y²-2xy=(x+y)²-2xy=a²-2b

x²-xy+y²=x²+2xy-2xy+y²-xy=x²+2xy+y²-3xy=(x+y)²-3xy=a²-3b

**I don't know how to ask me.

The square of x + the square of y = the square of (x + y) - 2xy = the square of a - 2b

The square of x - the square of xy + y = the square of (x + y) - 3xy = the square of a - 3b

(x+y) squared = x squared + y squared + 2*x*y; That is, the square of a = the square of x + the square of y + 2*b;

So the square of x + the square of y = the square of a - 2*b;