Original formula = A2-4+A-A2 = A-4

When a = 5, the original formula = 5-4 = 1.

Jiangnan Eco-food Processing Factory purchased a batch of mountain products with the mass of 1 10,000 kg, and carried out rough processing and fine processing according to market demand. It is known that the quality of finished products in mountain products is 3 times higher than that of roughing 2000 kg, so we can find the quality of roughing mountain products.

Solution: Let the mountain products mass of rough machining be x kg, and according to the meaning of the question, it is concluded that.

x+(3x+2000)= 10000。

The solution is x = 2000.

Answer: The mountain products mass of rough machining is 2000 kg. ..

In 2009, 80 teachers participated in the "Urban and Rural Teacher Assistance Project". After random investigation, it is found that each teacher can benefit 150 students on average. Please estimate how many students will benefit from this activity.

Solution: From the meaning of the question, 150×80= 12 000 (name)

A: 12000 students will benefit from this activity.

Inequality-3x+1>; The solution set of 4 is _ _ _ _ _ _ _.

Answer: x

Thinking analysis:

Examination center anatomy: this question examines and understands the inequality of one degree. Note that if both sides of the inequality are divided by a negative number, the direction of the inequality will change.

Thinking of solving problems: solve problems according to the steps of solving one-dimensional inequalities. Pay attention to the change of inequality direction.

Answer process:

Solution: -3x+ 1 > 4,-3x >; 3, x<- 1. Therefore, fill in: x.

Law summary: The common steps to solve linear inequality in one variable are: removing denominator, brackets, shifting terms, merging similar terms, and making the coefficient 1.

Point P (m- 1, 2m+ 1) is in the second quadrant, so the range of m is (-? < m< 1)

The solution set of inequality 2-x ≤ 1 is _ _ _ {x ≥1} _ _ _ _ _.

Thinking analysis:

Anatomy of examination center: this question examines the solution of linear inequality of one variable, and the topic is simple.

Thinking of solving the problem: according to the steps of shifting the term and transforming the coefficient to 1.

Answer process:

Solution: shift term, -x≤ 1-2,

-x≤- 1，

If the coefficient is 1, x ≥ 1.

So, the answer is: x≥ 1.

Law summary: the shift term should change sign, and the inequality property is 3. Both sides of the inequality should be multiplied or divided by a negative number that is not zero at the same time to change the direction of the inequality.

Solve inequality 2 (x-2) ≤ 6-3x and write its positive integer solution.

Answer:

Solution: Without brackets, you get 2x-4 ≤ 6-3x.

Shift term, 2x+3x ≤ 6+4.

Merge similar projects, 5x ≤ 10.

Divide both sides of the inequality by 5 to get x ≤ 2.

Its positive integer solution is 1, 2.

In order to educate students in patriotism, a school organized students to go to the show. There are two kinds of tickets, A and B. It is known that the unit price ratio of the two tickets is 4: 3, and the sum of the unit prices is 42 yuan.

(1) What is the unit price of two tickets?

(2) The school plans to spend no more than 750 yuan's funds to let 36 students in Grade 7 1 class watch first, and it is stipulated that tickets above 15 must be purchased. What are the purchase plans?

In order to encourage students to take part in physical exercise, the school plans to spend no more than 3200 yuan to buy a batch of basketball and volleyball. It is known that the unit price ratio of basketball and volleyball is 3:2, and the sum of the unit prices is 160 yuan.

(1) What are the unit prices of basketball and volleyball?

(2) If the total number of basketball and volleyball required is 36, and the number of volleyball purchased is less than 1 1, what are the procurement plans?

When a class graduates, the balance of class fees is 1.800 yuan. The class committee decided to spend no less than 270 yuan and no more than 300 yuan to buy souvenirs for the teachers, and the remaining money was used to buy a T-shirt or an album as souvenirs for each of the 50 students at the graduation party. It is known that each T-shirt is more expensive than each album in 9 yuan, so 200 yuan can just buy two T-shirts and five albums.

(1) What is the price of each T-shirt and each photo album?

(2) How many schemes are there to buy T-shirts and photo albums?