200 points for math inequality problems in the second year of junior high school

There are (x+1) people in group A; Group B has (y+1) people; There are W apples in each basket.

Then we get: 1) Eq. 13x + 6 = w

2) Eq. 10y + 5 = w

Method (1): Subtract equation (1) from equation (2) to get 10y + 5) - (13x + 6) = w - w10y - 13x - 1 = 0

y = (13x + 1)/10

Method (2): Substitution in equal amounts.

13x + 6 = w = 10y + 510y + 5 = 13x + 6

y = (13x + 1)/10

Analyze y = (13x + 1) 10, only when x = 13 can we ensure that w is greater than 100 and less than 200, y is an integer.

Therefore: x = 13 (person) y = 17 (person) from which group A is (x+1) person = 14 people; Group B has (y+1)=18 people; Each basket contains 185 apples.

Figured it out, hehe, divide that.

The first one has been said, and it's all too accurate!

The first one said it, and that's how it counts.

Solution: There are x people in group A, according to the topic.

100≤6+13(x-1)≤200

Because x is the number of people, it is a non-negative integer.

So the solution is 9 x 15

So 6+13(x-1) = 110,123,136,149,162,175,178,191

Let group B have y people, 100 5+10(y-1) 200 because y represents the number of people, which is a non-negative integer.

So 11 y 20

So 5+10 (y-1).

Because the number of apples in the two boxes is the same.

So only 6+13(x-1)=5+10(y-1)=175 meets the title, at this time x=14, y=18

A: There are 14 people in Group A and 18 people in Group B.

200 points! Violent!

So many people on the first floor that tried the method of trouble, on the top floor it was very clear.

Here comes the standard answer.

Solution: There are x people in group A, according to the topic.

100≤6+13(x-1)≤200

Because x is the number of people, it is a non-negative integer.

So the solution is 9 x 15

So 6+13(x-1) = 110,123,136,149,162,175,178,191

There are Y people in Group B, according to the title.

100≤5+10(y-1)≤200

Because y is the number of people, it is a non-negative integer.

So the solution is 11 y 20

So 5+10(y-1) = 105,115,125,135,145,155,165,175,185,195

Because the number of apples in the two boxes is the same.

So only 6+13(x-1)=5+10(y-1)=175 meets the title, at this time x=14, y=18

A: 14 people in Group A and 18 people in Group B.

Let Person A be Person X and Person B Person Y. Yes.

100=<6+13(x-1)=<200, then the solution is 94 13+18 At the same time, there are 100=<5+10(y-1)=<200, then 13x-2) 10 must be a positive integer, then 13x-2 must be a multiple of 10.

Then the last digit of 13x must be 2, then according to the multiplication formula, only 3*4=12 is 2, and the others are not, and then according to the value range of x, you can know that it must be 14, then you can calculate how many apples there are in each group, and you can calculate the number of people in group B.

I'll send you a message to explain it.

Here comes the standard answer.

The number of people in group A and group B is A+1 and B+1 respectively.

100＜13a+6＝10b+5≤200．

To make the mantissa of 13a+6 be 5, the mantissa of 13a needs to be 9, then the mantissa of a is 3, so it can be solved that a=13

Substituting, we get 13 13 + 6 = 10b + 5, b = 17 So A has 14 people and B has 18 people

There are x people in group A and y people in group B.

6+13（x-1）=5+10（y-1）

196〉13（x-1）〉94

195〉10（y-1）〉95

You can calculate the value range of x and y.

Then try to substitute the indefinite equation to solve x=14,y=18

Let X be the number of apples, then the number of apples is 13 (x-1) + 6 = 13x-7 The number of people in group B is: (13x-7 + 5) 10 =

100<13x-7<200

9≤x≤15

The number of people in B is.

Then the single digit of x is 4, which is an integer.

i.e. x = 14, the number of B is 18

The questions are not enough, so you can only try them one by one.

1.Save on electricity bills (.)

That is, the crack guess is 80% off.

2.The drug content of the shield is x

20%< (30*15%+50x) (30+50)<35%Solution: 23%.< x "Zhenyuan 47%< p>

A kind of insecticidal powder has 30,000 grams of Zhenke, the drug content is 15%, and now it is necessary to mix 50 kg of the same insecticidal powder with a higher drug content and it, so that the mixed drug content is greater than 20% and less than 35%, then the value range of the drug content x of the medicinal powder is?

Please explain the rough answer in detail

20%<(30×15％+50x%)/80<30%23

16 pcs. Let's say each worker used to make an average of x parts per day.

According to the meaning of the question, the following inequality is obtained.

x+10）*8>200

x+10+27）*4>(x+10)*8

Let's say each worker used to make an average of x parts per day.

After the first improvement of the working method, x+10 will be produced per day.

After the second improvement of the working method, x+37 units per day were produced.

Set up x passengers to complete the check-in every minute.

12+5×8≤5x

5x 52x because the number of people is an integer.

So x takes the smallest positive number = 11

A: On average, at least 11 passengers complete the check-in every minute.

On average, at least x passengers complete the check-in every minute.

5x greater than or equal to 12+8*5

5x greater than or equal to 52

x is greater than or equal to 52/5.

Because x is an integer.

So x=11

So on average, at least 11 passengers complete the check-in every minute.

Only by installing an X-stand can we meet the demand.

135+（10-2-3）x>=600

The solution is x>=93

i.e. at least 93 units per day.

600-135=465

A minimum of 93 units per day will be assembled within five days to meet the requirements.

5x>600-135

5x>465

x>93

Install at least 93 units per day to complete the task.

To do this kind of question, start with the question, at least how many units are installed every day, that is to say, there is a minimum value for the answer. 135 units were installed in 3 days, and there were 600-135 = 465 units left, and the remaining time was 10-3-2 = 5 days, 465 5 = 93, so the answer was to assemble at least 93 units per day.

Let ** of A be x and ** of b be y.

** from A is higher than ** of product B: x>y

Less than 2 times the value of product b**: x<2y

So: y is also based on the principle of inequality: both sides of the inequality are multiplied by a positive number and the sign of the inequality does not change, so: (100%+10%)y<(100%+10%)x<2(100%+10%)y

So: the answer to the first question is yes.

In the same way: x+10<2y+10 and 2y+10<2(y+10) can be seen from the transitivity of the inequality: x+10<2y+10<2(y+10) i.e. x+10<2(y+10).

So A's ** is still less than 2 times that of B.

The answer to the second question is also yes.

Condition b = < b is divided into three cases.

1。The turnover of a business pavilion in October was 5,000 yuan, and in December ** to 7,200 yuan, the average monthly growth percentage was ().

2。A certain drug used to cost 96 yuan per box, but due to two price reductions, it is now 54 yuan per box, and the average percentage of each price reduction is () yuan.

3。If the price of a product is reduced by 10% twice in a row, the original price of the product should be ().

4。If a commodity is going to be discounted due to the change of seasons, it will lose 25 yuan according to the 75% discount of the price, and 20 yuan will be earned according to the 90% discount of the price, so the pricing of this commodity is () yuan, and the purchase price is () yuan.

5。The sum of the square roots of two consecutive positive integers is 265, and these two numbers are ().

6。The length of one side of a triangular piece of iron is 50 cm less than the height of this side, and the area of this triangular iron block is 1800 cm, and the length of this side of the triangular iron block is () cm, and the height of this side is ().

Solution: (1) Yuan liter, Yuan liter.

Answer: Before the adjustment of the plan, the gasoline ** is, and the fuel tax is yuan liters;

2) It is more cost-effective to travel x kilometers per month than before the plan is adjusted, and consume 10 liters of fuel per 100 kilometers.

Fuel consumption liters per 1 km.

According to the title.

Solution x 1500;

Answer: The number of vehicles driven per month is in the range of 0 to 1500 kilometers, which is more cost-effective than before the plan adjustment

1) From the inscription, it can be seen that the fuel tax after the reform is 1 yuan, and it is more than the yuan before the reform, and the fuel tax before the reform and 93 gasoline before the reform can be obtained directly according to the title; (2) If the fuel consumption of a private car is 10 liters per 100 kilometers, the fuel consumption per kilometer is 10 100 = liters; Then let us travel x kilometers per month, according to the cost before the reform After the reform of the cost column inequality 120, the solution of the inequality can obtain the value range of x Answer: Solution:

1) Yuan liter, Yuan liter Answer: Before the adjustment of the plan, the gasoline ** is, and the fuel tax is Yuan liter; (2) Set the monthly driving x kilometers to be more cost-effective than before the scheme adjustment, fuel consumption of 10 liters per 100 kilometers fuel consumption per 1 kilometer according to the meaning of the problem 120 solution x 1500;Answer: The number of vehicles driven per month is in the range of 0 to 1500 kilometers, which is more cost-effective than before the plan adjustment

Use your own brain, do it with your hands, and learn well.

16 designs: Each worker used to make an average of x parts per day, and according to the question, the following inequality (x+10)*8>200

x+10+27）*4>(x+10)*8

Solution 15

Let's say each worker used to make an average of x parts per day.

After the first improvement of the working method, x+10 will be produced per day.

After the second improvement of the working method, x+37 units per day were produced.

Column inequality: 4(x+37)>8(x+10)>200 solves: 15Because x is an integer, x=16

A: Each worker used to make an average of 16 parts per day.

Solution: The world set up the principal to return to attack Brother X

then 130% x 700 115% x · (1+10%) x 20000

Therefore, when the investment is greater than 20,000 yuan, you can choose to make more profits at the end of the month.

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