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On the addition and subtraction of rational numbers: (+ 9) - (+ 21) (2) (- 12) - (+ 18) (3) 0 - (- 63) (4) (- 32) - 0 (5) (- 5.4) - 2.8 And: (6) (+ 37.9) - (- 5.1) (7) (- 15) - (8-9) (8) (8-2) - (14-9)
(1)(﹢9)-(﹢21) =9-21=12(2)(﹣12)-(﹢18) =-12-18=-30(3)0-(﹣63) =0+63=63(4)(﹣32)-0 =-32-0=-32(5)(﹣5.4)-2.8 =-5.4-2.8=8.2(6)(﹢37.9)-(﹣5.1) =37.9+5.1=43(7)(﹣15)-(8﹣9) =-15-8+9=-14(8)(8﹣2)-(14﹣9)...
Here are two questions. Observe the relationship between them and fill in the number represented by each figure
(1)□+△=16 □-4=16 □=( ) △=( )
(2)△+3=16 □+△=5 □=( ) △=( )
If you make a fool of yourself, it's not negative
Mathematical problem addition and subtraction
Xiao Ming and his three friends went boating. Originally, they agreed on the AA system, but the other three didn't have any change. Xiao ming helped the three people pay 70 yuan first. In the middle of the way, a few people said that they would let Xiao Ming give them the boat cheaply, so they gave Xiao Ming 40 yuan, and the boat belonged to them. Afterwards, Xiao Ming didn't know how to distribute it, and everyone didn't lose money
70 - 40 = 30 three people pay a total of 70 yuan minus 40 yuan paid by others, that is 30 yuan
Xiao Ming and three people will bear 30 yuan. There are four people with Xiao Ming, so each person should pay 30 / 4 yuan, that is 7.5 yuan
To sum up, each of the three people should pay Xiao Ming 7.5 yuan
RELATED INFORMATIONS
- 1. Cut out a square of the same size at each corner of the square paperboard with side length of 16 cm, and fold it into the sum of a cuboid without cover. 1. If the side length of the cut small square is xcm, please use X to indicate the volume of the carton. 2. When the side length x of the cut small square is 3cm and 3.5cm respectively, the volume of the two folded open cuboid cartons is compared.
- 2. Add addition, subtraction, multiplication and division or brackets to the appropriate place of the following formula to make the formula hold. 4 = 5
- 3. Multiply a number by 10, the number is 36 more than the original number, the original number is []
- 4. It can't be replaced by X. it can only be replaced by ordinary multiplication, division, addition and subtraction,
- 5. Some problems about arithmetic of significant number Is the operation process of 8.0421 / (6.038-6.034) + 30.9 like this?: 6.038-6.034 = 0.004 8.0421/0.004 = 2205.25 (since the least significant digit is one, the result should also retain one significant digit, so the original formula is about 2 * 10 ^ 3? So it can be added to 30.9. According to the highest suspicious digit, is the result still 2 * 10 ^ 3? There is another problem, Is the approximate number of 2205.25 taken first and then added by 30.9, or is the approximate number of 2205.25 and 30.9 taken first and then added by 30.9?
- 6. Fill in addition, multiplication, division, addition, subtraction and brackets to get the following answer. 123456 = 5
- 7. Numbers and algebraic expressions and equations (2) there are filling in the blanks and practical problems, within 10 minutes (multiplier sign: ×, division sign: △) Fill in the blanks: 1. Read a book, N pages a day, () 100 pages a day Xiao Xia is x years old and her father is (x + y years old). Ten years later, her father is () years older than Xiao Xia Fill in the blank ③ when m = 5, 5m = (), 5m + 1 = () There is a book. Xiaohua read 25% of it on the first day and one third of it on the second day. There are 120 pages left. How many pages are there in this book? There are 50 passengers on the bus. According to the conductor, the income of 1 yuan is 20 yuan more than that of 1.5 yuan. How many passengers buy 1.5 yuan tickets?
- 8. Take 1, 2, 3 and 4 and arrange them in a row from small to large. Insert a multiplier sign between these four numbers to get () different products This is a difficult math problem
- 9. 7 * 7, how to omit the multiplication sign?
- 10. Omit the multiply sign. A times 2 times B
- 11. Mixed operation of rational number addition and subtraction (+ 7 / 4) + (- 1 / 4) - (+ 16 / 7) - (- 16 / 7)
- 12. The subtraction rule of rational number is: subtracting a number is equal to what is the opposite of this number
- 13. Must negative numbers be rational numbers
- 14. How to calculate negative number before bracket when merging similar items?
- 15. Negative numbers in parentheses Merge similar items and evaluate them! For example: - b-7ab. Suppose B is 2 and a is 3, what is the format? - B need to add brackets?
- 16. -What is the square of 2? What is the square of (- 2)? Is the square of a negative number negative as long as there are no brackets?
- 17. According to the law of subtraction, the number of rational numbers According to the law of subtraction, the mixed operation of addition and subtraction of multiple rational numbers can be transformed into an operation that only contains addition. However, in a sum, the brackets of each addend and the family members in front of it are usually omitted, such as (- 8) - (- 10) + (- 6) + (+ 4), and it is rewritten to the sum that only contains addition_____________ In the form of an ellipsis______________ Read as______________________ Or________________ .
- 18. Find some problems of mixed operation of rational number addition and subtraction
- 19. How to do the 0-1 + 2-3 + 4-5 mixed operation of rational number addition and subtraction,
- 20. On the sign of inequality That is to say, multiplication or division of a negative number on both sides of an inequality requires a sign change, for example, negative half a > - 1. I remember the teacher said that negative should be changed, but our classmates said that it would not change, and it was right to do it, and - one in a