Initial Inequality Group Solution Application Problem Urgent !!!!!!!!

Solution: If the students in this mathematics learning activity group are organized into x groups, there are (7x+18) students, and according to the problem, 7x+18-10(x-1)<10

7x+18-10(x-1)>=0 ②

Solve the inequality to get x>6

Solve the inequality to get x<=9 1 3

Because x is an integer, x=7,8,9

A: If the students in this mathematics group are divided into 7 groups, there will be 67 students, if the students in this mathematics group may be formed into 8 groups, there will be 74 students, and if the students in this mathematics group may be formed into 9 groups, there will be 81 students.

Solution: If there are 10 people in each group, the number of groups less than 10 people in that group is y is y. The list is:

7x+18=10x+y 1 is less than or equal to y and less than 10 (x and y are positive integers).

Therefore, x=5, y=3 both: the number of possible groups is 5 groups, and the number of participants in the mathematics project activity group is 7*5+18=53 people.

If there are a total of x groups and a total of y people, then the simultaneous inequality group:

7x+18=y ①

10x-y>0 ②

10(x-1)-y<0 ③

Substitute for :

x>6；

Substitute for :

x<。

Hence x y

A and B have a total of 1 dime coin of 5 yuan, if A gives B 2 coins, it will be less than B's coin; If B adds 1 coin, it will be less than A's, and ask how many coins each of them has?

Solution: If A has x pieces, then B has 50-x pieces, so.

x-2<50-x+2 x+1>50-x-1 gives 24 because x is an integer and all x=25 or 26

So 50-x = 25 or 24

That is, A and B are both 25 pieces or A has 26 pieces and B has 24 pieces.

Solution: Add at least x grams of salt.

40+x) (1000+x) greater than or equal to 20% solution to x greater than or equal to 200

A: At least 200 grams of salt should be added to these seawater to achieve a salt content of at least 20%.

At least x grams of table salt.

40+x)/(1000+x)=20%

x=200A: At least 200 grams of table salt.

This is a question in Heilongjiang Next, I will give you the answer in ** mode The answer is as follows.

Analysis: (1) According to the known information and if the operator's purchase capital is not less than 5.76 million yuan and not more than 6 million yuan, the inequality group is listed and the car entry scheme is solved

2) List the profit function formula according to the known, find the maximum value, and choose the scheme (3) Obtain the answer by calculation and analysis according to the known.

Solution: If type A cars buy x, then type B cars buy (16-x) cars According to the question: 30x+42(16-x) 600 30x+42(16-x) 576, solution: 6 x 8

x is an integer, and x is taken

So there are 3 types: a, 6, 7, 8

b 10 9 8

2) Set the total profit to be W million yuan

According to the question: w = (32-30) x + (45-42) (16-x) = -x + 48

1 0, W decreases with the increase of X, when X = 6, W has a maximum value, W maximum = -6 + 48 = 42 (10,000 yuan) When purchasing 6 A type cars and 10 B type cars, the maximum profit can be obtained, and the maximum profit is 420,000 yuan

3) Let the mileage of electric vehicles be 10,000 kilometers

When 32+, the solution is: a=20 30

It is more cost-effective to buy a solar-powered car

Let the middle price of AB be 31, the power consumption cost of A is 10,000 plus the sales price is about 500,000 and greater than 10,000, and it is appropriate to choose B.

What kind of application questions?

1: From the meaning of the title, the stool filial piety + 2(20-x-y) = 42 is simplified: y = 20 - 2x ( 9 x jujube such as 2 , and x is an integer).

2：w = × 6x + 8y + 2 × 5 × 20 - x - y)

Y = 20 - 2x (w) = 336 - 9 x 2 (and x is an integer).

So when x = 2, i.e. when 2 cars are loaded with eggplant, the profit is maximum.

13 and 24 44 divided by 3 and 2/3 12 The third question seems to be written incorrectly.

1. Let the single digit be x, the ten-digit number is y, x-y=2, and the two-digit number is less than 30 and greater than 10 to determine that y is 2, and x=4 can be known

Solution: If the ten digits are x, then the single digit (x+2).

10＜10x+(x+2)＜30

10＜11x+2＜30

8＜11x＜28

8/11＜x＜28 /11

x can be 1 and 2

This two-digit number is 13 or 24

1. If the ten-digit number is x, then the single-digit number is x+2, and the two-digit number is 10x+x+2, then 10<10x+x+2<30 8 11=44, x>=12km3,(40+x) (1000+x)>=

40+x>=100+

60 x>=200/3

Assuming that there are x rooms in total, then a total of (8x+12) people can be arranged for 9 people in each room, and 2 rooms are vacated, that is, (x-2) rooms are enough, but it is impossible to vacate 3 rooms, and the inequality can be listed accordingly.

9×(x-3)<8x+12<=9×(x-2)9x-27<8x+12<=9x-18

Solution 30 = up to 38 rooms.

When x=30, the number of students is the lowest.

8x+12=252

This time, there were at least 252 students studying agriculture.

1.Set A and B each A and B bottles.

6a+9b=780, a+b=100, get a=40, b=602If A x bottle, then B 2x bottle.

6x+18x≤1200

then x 50

Fourth, a city produces an average of 700 tons of domestic garbage per day, all of which are processed by two garbage plants A and B, and it is known that Plant A processes 55 tons of garbage per hour, which costs 550 yuan; Plant B processes 45 tons of garbage per hour, which costs 495 yuan. If the cost of garbage disposal in the city is not more than 7,370 yuan per day, how many hours does Factory A need to dispose of garbage at least every day?

Solution: The garbage should be disposed of for at least a hour in the first place.

550a+（700-55a）÷45×495≤7370550a+（700-55a）×11≤7370550a+7700-605a≤7370

330≤55a

A 6A should dispose of garbage for at least 6 hours.

5. The school allocates a number of dormitories to the female students of the first class of the seventh grade, and it is known that there are less than 35 female students in the class, and if there are 5 students in each room, the remaining 5 people have nowhere to live; If there are 8 people in each room, one room will be vacant, and one room will not be satisfied. How many dormitories are there and how many girls are there?

Solution: If there is room A in the dormitory, the number of female students is 5A+5.

According to the title. a>0(1)

0<5a+5<35（2）

0<5a+5-[8（a-2）]<8(3)

Obtained from (2).

5<5a<30

From (1) 3a+8-5a+5<3

2a>10

a>5 by (2).

3a+8-5a+5>0

2a<13

a: "Then the value range of a is 5, then a = 6

There are 6 students and there are 3 6 + 8 = 26 books.

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