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East China Normal University Press first volume mathematics book mathematics problems! (East China Normal University Press) the answer to question 25 on page 84 of the first volume of junior high school mathematics book? There is a picture 1+3+5+7+9+11＝（）² From this we can guess that the sum of N consecutive odd numbers from the beginning is equal to? ……
1+3+5+7+9+…… +(2n-1) = the square of 2n * n / 2 = n
Answers to the 18 pages of mathematics textbook for the second semester of junior high school (East China Normal University Edition)
11,12,13,14,
There are two kinds of trees planted in schools. The number of known poplar trees is 56 more than half of the total number, and the number of Chinese fir trees is 14 less than one third of the total number. How many different kinds of trees are there?
A store will first pay 40% of the original price of the TV, and then give a 20% discount. After complaints from customers, the law enforcement department will impose a fine of 10 times of the illegal income of each TV
A fine of 2700 yuan will be imposed on Taiwan, which is the original price of American TV. 3. The long-distance bus from a to B used to travel for 7 hours. After opening the expressway, the distance is nearly 30 kilometers, and the average speed increases by 30 kilometers per hour. It only takes 4 hours to get there!
The number of poplar trees is 2 / 1 × 252 + 56 = 182, and the number of Chinese fir trees is 3 / 1 × 252-14 = 70. A: the original price is X Yuan x × (1 + 40%) × 80% - x = 2700 / 101.12x-x = 27000.12x = 27
The mathematics problems of the freshmen in China Normal University,
The reciprocal of the first, one and three fourths is ()
Second, find the maximum and minimum of the four numbers 3 and 13 / 2, 314%, 3 and 3 / 1 and X
Third, a pool has an inlet pipe and an outlet pipe, double pipe open 8 respectively can fill the empty space, a single outlet pipe 24 minutes to complete the full pool water, a single inlet pipe () minutes to fill the empty space
Fourth, 1 and 7 of 4 + 3.92 + 4.08 + 2 and 7 of 5, 2 and 5 of 3 * 6 + 2.3 + 3, 6 and 13 of 5 * 9.08 (simple calculation)
Fifthly, 1 and 5 / 2 + 2 and 5 / 4 * 3 and 7 / 4-8 and 2 / 1 (3 and 4 / 1-7 / 5 * 0.7) / (3-0.25) [1.25 + 92.6-1 and 3 / 2] / 3 and 7 / 2 (calculation)
What is the sum of the quotient of 6,47 plus 3 / 4 divided by 75
Please have someone to answer
(1)7/4
(2) 3 and 1 / 3 ＞ 3 and 2 / 13 ＞ 314%
（3）6
(4) 8 + 4 and 2 / 7 20.92.356
（5）2.9 1
(6) 47.05 what does "verify" mean
How many watts do physical home appliances know? How to calculate how many kilowatts per hour?
How many watts do household appliances know? How to calculate how many kilowatts an hour?
If there are three 1200 watt electrical appliances working at the same time
Can residents consume electricity?
1000 watts of electrical work is an hour of electricity;
If you have three 1200 watt electrical appliances at work at the same time, it should not be a big problem. It mainly depends on the size of your meter. If you install 30a, you can bring 6000 Watts at the same time
If the sum of the first seven frequency groups is 0.79, and the frequency of the remaining three groups is an equal ratio sequence, the common ratio of which is an integer and not 1, the frequency of the group with the largest frequency among the remaining three groups can be calculated
Let three groups of numbers be a, AQ, aq2, (a, Q ∈ n *, Q ＞ 1), then a + AQ + aq2 = 21, that is, a (1 + Q + Q2) = 21, and because 1 + Q + Q2 ＞ 3, a = 211 + Q + Q2 ＜ 7, and because q is an integer, ｜ A is a positive divisor of 21, so a = 1 or a = 3. When a = 1, we can get 1 + Q + Q2 = 21, that is, (q-4) (Q + 5) = 0, we can get q = 4, or q = - 5 (rounding off). The group with the largest frequency is aq2 = 16, and the frequency is 16100= When a = 3, we can get 1 + Q + Q2 = 7, that is, (Q-2) (Q + 3) = 0, the solution is q = 2, or q = - 3 (rounding off), the group with the largest frequency is aq2 = 12, and the frequency is 12100 = 0.12
Is the unit of moment of inertia in E = 1 / 2 (J ω ^ 2) in the calculation formula of rotational kinetic energy kg · m ^ 2? Is the unit of calculated kinetic energy J (joule)?
Dimensional analysis:
[½ Iω²] = [Iω²] = kg•m²•Rad/s² = kg•m²/s² = N•m = Joule
All kinetic energy in Si is Joule, including translational kinetic energy and rotational kinetic energy
In atomic physics, however, joules are so large that electron volts are often used
Solution equation: x ^ 2-2x-15 + [36 / (x ^ 2-2x)] = 0
Let x ^ 2-2x = t, where:
t-15+36/t=0
t^2-15t+36=0
T = 3 or T = 12
When x ^ 2-2x = 3, the solution is x = 3 or x = - 1
When x ^ 2-2x = 12, the solution is x = 1 + √ 13 or x = 1 - √ 13
How does electricity calculate power watt?
For example, how many watts is the 220 V 0.14 a equipment? How to calculate? Please write the formula in simplified Chinese, such as "W watt", "a ampere" and "V volt"
Power (W) = voltage (V) * current (a)
Equipment power of 220 V 0.14 a = 220 V * 0.14 a = 30.8 w
0.875 is a fraction
7/8
The calorific value of gasoline is 4.6 × 10 / 7 joules per kilogram. What is the heat released by completely burning 210 grams of gasoline
Q=mq=0.21kg×4.6×10^7J/kg=9.66×10^6J
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