Application problem, to use the formula to solve, the problem below Make a parallelogram with iron wire. The two adjacent sides are 20 cm and 10 cm long respectively. Pull its two diagonal vertices to turn it into a rectangle. What is the area of the ball rectangle?

The length of parallelogram is still 20cm and 10cm
The area of a rectangle is length times width
20 x 10 = 200 square centimeters

10 different types of practical problems in the first semester of junior high school!
First type out 10 questions, and then type the answers. There should be analysis process and breakthrough point (equivalent relationship), novelty and different solutions

1. There are 84 tons of water in a pool. There are two drainpipes A and B. pipe a discharges 2.5 tons of water per hour, and pipe B discharges 3.5 tons of water per hour. If pipe a is opened first and pipe B is opened after 2 hours and 24 minutes, how many hours can pipe a discharge the water in the pool?
Set B pipe to open for X hours to drain the water in the pool
3.5*X+（2.4+X）*2.5=84
3.5*X+6+2.5*X =84
（2.5+3.5）*X+6 =84
6X+6 =84
6X =84-6
6X =78
X =78/6
X =13
X+2.4 =15.4
A: the water in the pool can be discharged 15.4 hours after the opening of the tube
2. The correspondent sent the message from a to B, and then returned to a immediately. It took 3 hours and 52 minutes to get the distance between a and B. the speed was 30 km / h when he went and 28 km / h when he came back
The distance between a and B is x km
X/30+X/28 =3 13/15
28X/840+30X/840 =58/15
58X/840 =58/15
58/15*（840/58X）=1
X =56
A: the distance between a and B is 56 kilometers
3. A walks 5 kilometers per hour, and B goes after a by bike after 2 hours
(1) If B's speed is 20 km / h, how long does it take B to catch up with a?
5 × 2 = 10 (km) 10 / (20-5) = 2 / 3 (H)
(4) If you want to catch up with a when B walks 14 kilometers, what's the speed of B?
14 / 5 = 2.8 (H) 14 / 0.8 = 17.5 (km / h)
5. Party A and Party B practice walking on the 400 meter circular track. Party B walks 80 meters per minute. The speed of Party A is 1 / 4 of that of Party B. now Party A is 100 meters in front of Party B. how many minutes later will the two meet for the first time?
1.25 * 80 = 100 (km) 300 / (100-80) = 15 (min)
6. () 4 = 81 [the fourth power of X is 81, find x]
X^4=81
X = ± 4 times root sign (81) = ± 3
7. Calculate (- 2) 14 Power * (negative half) 15 power
(- 2) 14 Power * (- 1 / 2) 15 power
=(- 2) 14th power * (- 1 / 2) 14th power * (- 1 / 2)
=(- 2 * (- 1 / 2)) 14th power * (- 1 / 2)
=The 14th power of 1 * (- 1 / 2)
8.-3/2*[（-2/3）²-2]
-3/2*[（-2/3）²-2]
= -3/2*[4/9-2]
=7/3
9.16÷（-2）³-（-1/8）*（-4）
16÷（-2）³-（-1/8）*（-4）
= -2-1/2
=-5/2
10.a：6 -6 -6 -6 2 -1.5
b：4 0 4 -4 -10 -1.5
It is known that two points a and B represent two points a and B on the number axis
(1) Distance between a and B points:
(2) If the distance between two points of AB is D, what is the relationship between D and ab?
(3) Find all the qualified points P so that the sum of their distances to 10 and - 10 is 20, and find the sum of all these integers
(1) Distance between a and B: 26 10 2 120
(2) If the distance between two points of AB is D, what is the relationship between D and ab? D = / a-b/
(3) Find all the qualified points P so that the sum of their distances to 10 and - 10 is 20, and find the sum of all these integers
-9 -8 - 7...0.7 8 9
The sum of all these integers is 0

Give me the formula, too
In order to promote LG air conditioner, a store can pay twice for the purchase of air conditioner on the new year's day of 2003, and pay a sum of money in advance at the time of purchase. The rest and its interest (annual interest rate is 5.6%) will be paid off on the new year's day of 2004. The air conditioner is 8224 yuan per unit. If the two payments are the same, how much will it pay each time?

Let x yuan be paid each time
The result is: (8224 - x) × (1 + 5.6%) = X
2.056 x = 8224 × 1.056
x = 4224
A: how much do you pay each time? 4224 yuan

The second semester of junior one,
1. It takes 12 days for a to do it alone, 15 days for B to do it alone, and 20 days for C to do it alone. Originally, it was planned to do it in 7 days, but actually a and B did it first for a few days, and then C joined in, one day ahead of schedule. How many days did a and B do it first? How many more days did C join in?
2. The concentration of disinfectant A is three times of that of disinfectant B. after taking out 120g of disinfectant A and 240g of disinfectant B and adding 40g of water, the measured concentration is 30%. What are the concentrations of disinfectant A and disinfectant B?
3. A and B run on a 400m circular road, and B runs faster than A. they start at the same place at the same time, run in the opposite direction, and run once every 1min. If they run in the same direction, run once every 8min. Find the running speed of a and B

1、 Let AB do X days and C do (6 - x) days
Lie equation: (1 / 12 + 1 / 15) · 6 + (6-x) (1 / 20) = 1
Calculation and answer process
2、 Let B be x and a be 3x
（120·3X+240·X）/（240+120+40）=0.3
3、 Let a be x and B be y meters per second
（x+y）·60=400 （y-x）·8·60=400

Application of equations in the first semester of junior high school (formulas and answers)
1. A square table has four legs. If one cubic meter of wood can be used to make 50 tables or 300 legs, now we need to use 5 cubic meters of wood to make a square table. Please design how much wood can be used to make a table and how many legs can match the square table?
2. An individual bookstore sells two kinds of books a and B in one day. The profit of a kind of books is 25%, and the total sales amount is 1560 yuan; the loss of B kind of books is 10%, and the total sales amount is 1350 yuan. How much is the total profit (or loss) of the bookstore?
3. The age of the three brothers is 30, the age of the big brother minus 2, the age of the second brother plus 2, the age of the third brother is exactly the same, what are the ages of the third player?
4. In order to promote a certain kind of air conditioner in a shopping mall, the purchase of the air conditioner on the national day of 2003 can be paid in two installments. A sum of money will be paid in advance, and the rest and its interest will be paid off on the national day of 2004?

1. If x cubic meter of wood is used as the table top, then 50x: 300 (5-x) = 1:4, that is, 50x * 4 = 300 (5-x), then x = 3 is solved. Therefore, if 3 cubic meter of wood is used as the table top, and 2 cubic meter of wood is used as the table legs, then the square table is 50 * 3 = 150. 2

Practical problems need formulas or equations
Unit 1 test questions, unit 2 test questions, mid-term test questions, unit 3 test questions, unit 4 test questions, final test test questions, fast,

1. The distance between Shenzhen and Guangzhou is 165 kilometers. A bus travels 65 kilometers per hour, and a truck 45 kilometers per hour. The two vehicles leave each other at the same time. When do the two vehicles meet on the way? How many kilometers does the bus travel when they meet?
2. Mischievous and dad run in the school track and field. Mischievous runs one circle with 4 points, dad runs one circle with 6 points. Mischievous and dad walk in the same direction from the starting point at the same time. How many points can they meet at the starting point for the first time? How many laps did they run when they met?
3. The distance between a and B is 539.2km, and a small car and a big car leave from a and B at the same time. Five hours later, the two cars are 34.2km apart and do not meet each other?

1. 165 ÷ (65 + 45) = 1.5 hours
The bus has gone: 1.5 * 65 = 97.5km
2. 12 points
Naughty run: 12 △ 4 = 3 circles
Dad ran: 12 △ 6 = 2 laps
3. (539.2-34.2-55 * 5) △ 5 = 46 km

Write arithmetic
Practical questions
1. A shoe store sells a batch of leather shoes. At the beginning, the price is set at 80% of the profit. After 75% of the shoes are sold, the remaining shoes will be sold at a 60% discount. What percentage of the profit can be made if all the shoes are sold out?
2. Mingdao primary school needs to buy 60 football. Now there are three supermarkets (a, B and C) to choose from. The price of each football in the three supermarkets is 25 yuan, but the preferential way of each supermarket is different
Supermarket a: 2 free football for every 10 football bought
Supermarket B: 20% off if you buy more than 10 football
C Supermarket: 30 yuan in cash for every 200 yuan shopping
If you are the master of the general affairs office, which supermarket will you choose to buy? Why? Please write down the calculation process
3. Xiaoming's mother bought a kind of fresh Lentinus edodes. The moisture content was 99%. After drying, the moisture content dropped to 98%, so the quality was reduced by 450 grams. How many grams of fresh Lentinus edodes were bought at the beginning?
4. Xiao Ming read an extra-curricular book. On the first day, he read one sixth of the whole book, and on the second day, he read 20% of the whole book. On the first day, he read 8 pages less than on the second day. How many pages are there in this book?

1.) 80% * 75% + 60% *% 252) supermarket a: the actual price of each ball is: 25 * 10 / (10 + 2) = 20 and 5 / 6; supermarket B: the actual price of each ball is: 25 * 0.8 = 20; supermarket C: the actual price of each ball is: (200-30) / (200 / 25) = 21.25

Mathematics application problem (all have formula, except the first problem)~
1. △ 3 / 5-2 / 7 × 7 / 10 = 2 / 5 1 △ (4 / 5 ×? - 1 / 5) = 3 = () () () 2. The primary and secondary schools in the new city have carried out waste paper recycling activities, and a total of 70 tons of recycled paper have been produced. It is known that the recycling rate of recycled paper from waste paper is 80%. How many tons of waste paper have been recycled in primary and secondary schools in the new city?
3. 95% of the students in huahutong primary school have taken part in accident insurance. There are 24 students who have not taken part in the insurance. How many students have taken part in the insurance? 4. A bucket of oil costs 5 / 8, which is exactly 25kg. How much is the weight of this bucket of oil?
5. 800 kg refined salt needs to be packed in bags. If 1 / 4 kg is packed in each small bag, how many small bags are needed?
6. Li Wei reads a story book. He reads one seventh of the whole book every day. After three days, the rest is 20 pages more than what he has read. How many pages is the story book?
7. For a job, Party A will finish it in 6 days and Party B will finish it in 8 days. After 4 / 3 days of cooperation, what percentage of the work is left? If Party A continues to finish the rest, how many days will it take?
8. There are two classes to travel. If you buy tickets separately, the two classes should pay 1166 yuan. If you buy tickets together, the total ticket price is 880 yuan. How many people are there in the two classes? The ticket price is as follows: 12 yuan for 49 people; 10 yuan for 50-99 people; 8 yuan for more than 100 people
9. There are two bags of rice, a and B, which used to be the same weight. If 10kg is taken from bag a and poured into bag B, then the rice in bag a is 1 / 3 of that in bag B. how many kilograms of rice are there in bag B now?
10. Xiao Ming cut a piece of iron wire. For the first time, he cut off half of the whole length. He cut off the remaining half in this order. After three times, he measured the remaining iron wire, which was exactly 3 / 8m. How many meters was cut off for the first time?

1. What do you write? I don't understand
2. 70 △ 80% = 87.5 tons
3. 24 (1-95%) = 480 persons
4.25÷（5/8）=40
5. 800 △ 0.25 = 3200 bags
6. Suppose the whole book has x pages
4X/7-3x/7=20
X=140
7.（1）.1-4/3（1/6 1/8）=11/18
（2）11/18÷1/6=11/3
8. There are 880 △ 8 = 110 students in the two classes
If the number of people in each class of the two classes is between 50 and 99, the two classes will pay a total of 110 × 10 = 1100 yuan to buy tickets respectively. However, the question tells us that the two classes will pay a total of 1166 yuan to buy tickets respectively. Therefore, it can be imagined that the number of people in one class is between 1 and 49
Let X be the number of students in the class of 1-49, and 110-x be the number of students in the other class
12X 10×(110-X)=1166
12X 1110-10X=1166
2X=66
X=33
110-33=77
9. Let a and B weigh XKG each
X-10=1/3（X 10）
X=20
Now B has: x 10 = 30
This problem can be solved by drawing
Cut off 3 / 8x4 = 3 / 2m for the first time

20 drops of water just fill the volume of 1 cubic centimeter. How many drops of water can fill the volume of 10000 cubic meters?

2*10^8

Application problem, to use the formula to solve, the problem below Make a parallelogram with iron wire. The two adjacent sides are 20 cm and 10 cm long respectively. Pull its two diagonal vertices to turn it into a rectangle. What is the area of the ball rectangle?