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First line 1, second line 234, third line 56789 First line 1 Second line 234 Third line 56789 . (1) How to find the number x of a line? For example, the number 12 of line 31 (2) How to find a number in the first line? For example, 2007
Method 1: this question is a rule. If you look carefully, you can find it. What is the relationship between the last number in each line and the number in each line? (1) the 12th number in line 31 is the square of 30 plus 12, that is 912; (2) because the square of 44 is 1936, and the square of 45 is 2025, so 1936 is the nearest square from 2007, 2007-1936 = 71
What's the difference between unit "1" in mathematics and natural number 1
Unit "1" in Mathematics
Finding the unit "1" correctly is not only the key to solving the score (percentage) application problems, but also the key and difficult point for teachers to teach such application problems. There are always key sentences (sentences with score rate) in each score application problem. How to find the unit "1" from the key sentences, I think we can consider from the following aspects
1、 Number of parts and total
For example, China's population accounts for about 1 / 5 of the world's population, the world's population is the total, China's population is the partial, so the world's population is the unit of "1". For another example, the canteen bought 100 kg of cabbage, ate 2 / 5, and the canteen bought 100 kg of cabbage, How many kilos did you eat? Here, the total number of cabbages bought in the canteen is the total number, and the part number eaten is the part number, so 100 kilos of cabbages is the unit "1". It's very easy to find out the total number and part number, and determine the unit "1" in order to solve this kind of fractional application problems
2、 Comparison of two kinds of quantity
There are many key sentences comparing the two kinds of numbers in the practical questions of fractions. Some are "Bi" sentences, while others are not "Bi", but "Zhan", "Shi" and "equivalent" with directional characteristics. In the key sentences with "Bi", the number after "Bi" is usually used as the standard quantity, For example, the number of male students in class 6 (2) is 1 / 2 more than that of female students. It is based on the number of female students (unit "1"), and the number of male students more than that of female students is used as the comparison quantity. When there is no comparison between the two quantities, we usually find the score to see who is "accounted for", "equivalent to" who is "and" is ", For example, the width of a rectangle is 5 / 12 of its length
3、 Original quantity and current quantity
It is difficult to find the unit "1" of this kind of fraction application questions. For example, the volume of water increases by 1 / 10 after it becomes ice, and the volume of ice melts into water, The volume is reduced by 1 / 12. Who is the unit "1" for the quantity of water and ice like this? Is the unit "1" the same in the two key sentences? It's not easy to find the unit "1" by using the two methods mentioned above. In fact, we just need to see who is the original quantity? The original quantity is the unit "1"! For example, when water turns into ice, the original quantity is water, Then water is unit "1". Ice melts into water. The original quantity is ice, so the volume of ice is unit "1"
2. The natural number 1 is a pure number
2012 people's education press summer homework fifth grade mathematics rules
Review the basic knowledge points: 1, find the cycle; 2, the number of cycles; 3, what is the remainder is the number. 4, to calculate the total number of each project, can be divided into three steps: (1) each several as a group; (2) each group has a few; then multiply the total number of groups
Three consecutive natural numbers are between 100 and 200, the smallest of which can be divided by 3, the middle by 5, and the largest by 7. Try to write all these three natural numbers
These three consecutive integers are between 100 and 200, so the number of hundreds is determined as 1. Because the middle number can be divided by 5, the last number is 0 or 5, so the decimal number of hundreds is 1, and the number of ones is 9 or 4. If the decimal number of hundreds is 9, it can be divided by 3, so the number of tens is 2, 5, 8
The fourth root of 25
25^(1/4)=5^(1/2)≈2.236
There is a batch of goods in the warehouse. 15 tons were transported in the first day, and 8 tons more in the second day than in the first day. 1425 tons of the total weight of this batch of goods are left. How many tons of this batch of goods are there?
A: there are 200 tons of this batch of goods
Simple calculation 1 + 2-3-4 + 5 + 6-7-8 + 9 +. + 2013
1+2-3-4+5+6-7-8+9+…… +2007+2008-2009-2010+2011 -2012+2013=1+ （2-3-4+5）+（6-7-8+9）+…… +（2004-2005-2006+2007）+（2008-2009-2010+2011） -2012+2013=1+0+0+…… +0+1=2
The application problems of quadratic equation of two variables,
A vegetable company has acquired 140 tons of certain vegetables, which are ready to be processed and sold on the market. The processing capacity of the company is that it can process 6 tons of refined vegetables or 16 tons of rough vegetables every day. Now it is planned to complete the processing task in 15 days. How many days of rough processing and finishing should the company arrange to complete the task on schedule? If the profit of each ton of vegetables after rough processing is 1000 yuan, and that after finishing is 2000 yuan, According to this arrangement, how much profit can the company make from the sale of these processed vegetables
X+Y=15
6X = 16y = 140, x = 5, y = 10
What's next?
Your solution is not right. The correspondence equations x + y = 15
6x+16y=140
The solution is x = 10, y = 5
Next, we should work out the quantity of finishing: 6 * 10 = 60 tons, and the profit is 60 * 2000 = 120000 yuan
Quantity of rough machining: 16 * 5 = 80 tons, profit: 80 * 1000 = 80000 yuan
The total profit is: 120000 + 80000 = 200000 yuan
The distance between a and B is 240 meters. A local train starts from a place and travels 60 kilometers per hour. At the same time, an express train starts from B place and travels 90 kilometers per hour?
The pursuit problem in the typical application problems of primary school mathematics, such as this simple formula can be directly used:
Pursuit time = pursuit distance (fast slow), i.e
240 ÷ (90-60) = 8 (hours)
A: slightly
423*9/25*15/4-14/5*0.423*125
Original formula = 423 * (9 / 25 * 15 / 4-14 / 5 * 1 / 1000 * 125)
=423*（135/100-14/5*1/8）
=423*（135/100-35/100）
=423*100/100
=423
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