1.（10-11）×（11-12）×（12-13）×… ×（99-100）=_____ . 2. - 1 - (- 5 and 1 / 2) × (+ 3 / 11) [main process] 3.2 / 3 × (- 1 / 2) - (- 1 and 1 / 2) × (- 1 and 1 / 3) [main process] 4. Simple calculation: 15 × (- 3 / 5 + 1 / 3) - 24 × (5 / 12-7 / 8) [main process] 5. Using a simple method to calculate: - 8 × (- 13 and 7 / 12) - (- 5) × (- 13 and 7 / 12) + 4 × (- 13 and 7 / 12) [main process] 6. Two kinds of operations are defined as follows: + 0means "+ there is a circle outside" × "means" × there is a circle outside ". For any two rational numbers a, B has: a + ○ B = a + B-2, a ×0b = a · B-2. Find the value of - 4 × (6 + ○ 8)

1.（10-11）×（11-12）×（12-13）×… ×（99-100）=_____ . 2. - 1 - (- 5 and 1 / 2) × (+ 3 / 11) [main process] 3.2 / 3 × (- 1 / 2) - (- 1 and 1 / 2) × (- 1 and 1 / 3) [main process] 4. Simple calculation: 15 × (- 3 / 5 + 1 / 3) - 24 × (5 / 12-7 / 8) [main process] 5. Using a simple method to calculate: - 8 × (- 13 and 7 / 12) - (- 5) × (- 13 and 7 / 12) + 4 × (- 13 and 7 / 12) [main process] 6. Two kinds of operations are defined as follows: + 0means "+ there is a circle outside" × "means" × there is a circle outside ". For any two rational numbers a, B has: a + ○ B = a + B-2, a ×0b = a · B-2. Find the value of - 4 × (6 + ○ 8)

1 (-1)^90=1
2 =-1+11/2*3/11=1/2
It's very simple. Children should use their own brains

1. (2 + 1) (2? 2 + 1) ··· (2n of 2 + 1) 2.100²-99²+98²-97²····+2²-1²

1, (2-1) (2 + 1) (2 2 + 1) ···· (2n square of 2 + 1) = (2-1) ···· (2n power of 2 + 1) = 4N of 2-12.100 ····· (2n of 2 + 1) = 4N of 2 = (100 + 99) (100-99) + (98 + 97) (98

(1) (x-3) 2 = 16 (find x) （2）－27（x+30）=64

（1）（x－3）² = 16
X-3 = 4 or x-3 = - 4
X = 7 or x = - 1
(2)－27（x+30）=64
x+30=-64/27
x=-30-64/27
x=-874/27

1、－8-24+（－73）×56 2. The third power of 2 × (- 12) + 3 × (- 13) - the fourth power of 4 × (- 14) 3. The second power of| - 5| - 7 - (minus 1 / 3) -|5 divided by (- 6)| (write the process) I've done it many times and I'm sorry to come

1、-32 - 4088= -4120
2、-24 -6591-153664=-160279
3、5-49+1/3-5/6=-44.5

Several math practical problems in junior high school 1. The express train runs 72 km / h and the slow train runs 60 km / h. They also travel from station a and station B. before the two trains meet, the local train stops for 1.5 hours for some reason. When the two trains meet, the distance of the express train is three times that of the slow train. What is the distance between the two stations? 2. The following table shows the quality and profit of three kinds of vegetables of a, B and C. an automobile company plans to ship the three kinds of vegetables to other places for sale (each vehicle is fully loaded, and only one kind of vegetable can be loaded). If 8 vehicles are used to ship B, how many cars will be allocated for the two kinds of vegetables? How many of them are each? (just answer) Form: A, B, C Tonnage per vehicle: 21 1.5 Profit (100 yuan) per ton of vegetables Add a: Xiaoming high school entrance examination pass number is composed of four numbers, the four digits have the following characteristics: 1. Its thousand digit number is 1. 2. Move the thousand digit number to the right to make it a single digit number, then the new number is 5 times less than the original 49. Please introduce the minor name examination number according to the above characteristics Just a few By 9:00, it's due tomorrow I'll offer you a reward! The first question has been solved. What I want is the second and third answer!

Question 1: 240 km
The third question: the examination number is 1990
Given that the number of thousands is 1, so take the last three numbers as a whole and set them as ABC
(1000+ABC)*5-49=10*ABC+1
ABC=990
So the new number is 9901

1. A and B climb a mountain. A climbs 10 meters every minute, and starts 30 minutes first. B climbs 15 meters at the same time. How long does it take for a to climb the mountain? How high is the mountain? 2. The electric locomotive and the maglev train start at the same time from the two places 298 km away from each other. The speed of the train is 20 km faster than that of the locomotive. Half an hour later, the two trains meet. What is the speed of the two cars? 3. One person bought two kinds of cloth with 540 rubles, a total of 138 Russian feet, including 3 rubles for blue cloth and 5 rubles per Russian foot for black cloth. How many Russian feet did one person buy for two kinds of cloth?

If the locomotive speed is x km / h, then the train speed is (5x + 20km) / h (x + 5x + 20) × 0.5 = 2

The solution of one variable linear equation In order to encourage water conservation in a city, the charging standards of tap water are as follows: 0.45 yuan / T is charged for the water consumption of no more than 10 tons per household per month; 0.80 yuan / T is charged for the part of more than 10 tons but not more than 20 tons, and 1.5 yuan / T for the part over 20 tons The solution of one variable linear equation

According to the meaning of the title, the water consumption of Huanhuan's house in October was more than 2ot
If the water consumption of Huanhuan house in October is t tons, then: 10 * 0.45 + 10 * 0.8 + (T-20) * 1.5 = 14
T = 21

A city charges water according to the standard: if the water consumption does not exceed 20t, it will be charged at 1.2 yuan / T; if it exceeds 20t, the excess part will be charged at 1.5 yuan / T. The average water charge of a family in May is 1.25 yuan / T, so how much should the family pay for water in May () A. 20 yuan B. 24 yuan C. 30 yuan D. 36 yuan

Because the water consumption does not exceed 20t, the charge is 1.2 yuan / T, and the average is 1.25 yuan
Suppose: pay X Yuan in May
20*1.2+（x-20)*1.5=1.25x
24+1.5x-30=1.25
1.5x-1.25x=30-24
0.25x=6
x=24
24 * 1.25 = 30 yuan
So you should choose C

At present, 190 pieces of iron sheets are used to make boxes. Each sheet of iron can be used to make 8 boxes or 22 boxes bottom. One box body and two box bottom are matched to form a complete box. How many pieces of iron sheets are used to make the box body and box bottom match?

Let x sheet iron be the box body and Y sheet iron as the bottom
x+y＝190
2×8x＝22y. ，
have to
x＝110
y＝80. ．
A: 110 sheets of iron are used for the body and 80 sheets for the bottom

The first batch of 270 computers will be shipped in the near future. After contacting with a logistics company, it is known that 45 computers can be installed in each car of type A and 60 computers can be installed in each car of type B. It is known that the freight of type a vehicles is 350 yuan per vehicle, and that of type B vehicles is 400 yuan per vehicle One more car is used for model B than model a, and the freight cost is less than that of any type of vehicle. According to this scheme, how many cars of a and B are needed and how much is the freight?

If X type a vehicles are required, then B-type vehicles (x + 1) are required. As a result, 6 vehicles are required for transportation by A-type vehicles, and the freight is 2100 yuan; if B-type vehicles are used alone, 5 vehicles are required, and the freight is 2000 yuan,
According to the meaning of the title
45x+60(x+1)≥270
350x+400(x+1)＜2000
Solution 2 ≤ x < 32
15，
Because the number of cars used should be a positive integer,
So x = 2
At this time, the freight is 350x + 400 (x + 1) = 350 × 2 + 400 × 3 = 1900 (RMB),
Therefore: according to this plan, 2 A-type cars and 3 B-type cars are needed for transporting computers, and the freight is 1900 yuan