Mathematics in grade one of junior high school: is π 2 / 2 a fraction? Is it a rational number Our teacher said that those with π are not fractions, right

π is a fraction, but not a fraction, because it is not a rational number

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1. Rational number multiplication [- 10] * 3 * [- 1 / 2] * [- 5 and 1 / 3] * 4 / 5 [- 10] * 3 * [- 1 / 2] * [- 5 and 1 / 3] * 4 / 5 [- 17] * [- 2] * 34 * 0 * [125] 16 * [- 18] * 0.25 * [- 1] [- 4] * [+ 8.9] * [- 0.25] [- 2] - [+ 5 / 6] * [- 3 / 5] - 4-2 * 32 + [- 2 * 32] [7 / 6 + 5 / 4 + 3 / 18] * 36 [1 / 3 2 - [1 / 3-6 + 5 / 12] * 2.4] * 5
2. Positive rational number: 3, 2 / 3, 50, 2.5, 4 / 3. Negative rational number: - 7, - 2 / 3, - 0.8, - 10.5, - 11. Please select 2 positive rational numbers and 2 negative rational numbers from them, and then use the three symbols in "+, -, ×, △" to perform three operations on the selected 4 numbers, so that the operation result is 0, and write two formulas that meet the conditions
3. On the concept of rational number in the first day of junior high school It is said in the book that generally, a minus sign is added before the rational number, but there is also a minus sign at the beginning of some formulas, and there are no brackets. Does it mean the opposite number or the negative number? Please help me, It's not a minus sign, it's a similar sign For example: -50 divided by 2 times (1 / 5) - 2 times (- 3) times (- 4) Just for an hour,
4. Who has the exercise of rational number in the first grade of junior high school Any question is OK, as long as the classic point, often test or uncommon questions on the line, can you also send the answer to it
5. The concept of multiplication and division of rational numbers in the first year of mathematics of people's Education Press In urgent need of brothers and sisters
6. rational number
7. The following is the definition and operation of rational numbers a and B: a # B = A-B + 1. Is a # B equal to B # a? Why? I know it's not equal, mainly I want to know how to write the reason, and the reason is written by example
8. Junior high school, addition and subtraction of rational numbers. (- 7) - 9 - (- 3) + (- 5), - 4.2 + 5.7-8.4 + 10, (- 1.3) - (- 3.2), - 1 / 4 + 5 / 6 + 2 / 3-1 / 2 It's a process, please
9. How to move two points in ABC so that the number represented by three points is the same? There are several ways to move? A is negative 2, B is negative 1, C is 2
10. How to move the two points of a, B, C so that the numbers represented by the three points are the same? What kinds of moving methods are used? ABC is at the positions of - 5, - 1, 1 respectively
11. If the sum of two rational numbers is 0, then the product of the two numbers must be equal to minus one If the sum of two rational numbers is 0, then the product of the two numbers must be negative one, right or wrong, why
12. The following statement is wrong () A. Any rational number has reciprocal B. the product of reciprocal numbers is 1C. Reciprocal numbers have the same sign D. 1 and - 1 are reciprocal numbers
13. 1. If the rational numbers a and B are opposite to each other, then the sum of the two numbers is? If the rational numbers a and B are reciprocal to each other, then the product of the two numbers is? 2. Calculation (- 0.25) x0.5x (- seventy and three fifths) X4 (- one and two thirds) x (- 18) - 15x one and two thirds Ten and four fifths x (- 25) We need the formula!
14. There are only four rational numbers, of which the sum of every three numbers is 3, 5, 13 and 15 respectively. How much is the product of these four rational numbers emergency
15. Write a number whose product with 2 √ 3 is a rational number
16. If the sum of products of two numbers is known and one of them is - 2 and 3 / 7, find another number Given that the quotient of two numbers is - 3 and 1 / 2, and one of them is 2 and 1 / 3, find another number The title says that the product of two known numbers is 1, so it's wrong.
17. Using the mixed operation of addition and subtraction of rational numbers, (- one fifth) + two fifths + (- three fifths) Using the method of mixed operation of addition and subtraction of rational numbers, 1. (- one fifth) + two fifths + (- three fifths) 2.（-7）-（-5）+（-4）-（-10） 3.4.7-（-8.9）-7.5+（-6） 4. - half + (- one sixth) - (- one fourth) - (+ two thirds) 5. - half - five and one fifth + 4.5 + Half - 4.5 + five and one fifth 6.（-2.5）-（+2.7）-（-1.6）-（-2.7）+（+2.4） 7. 3 / 4-7 / 2 + (- 1 / 6) - (- 2 / 3) - 1
18. Is Dirichlet function continuous almost everywhere on R? I know it's discontinuous everywhere. Is it continuous almost everywhere in real change?
19. Why is Dirichlet function not continuous? It is said that Dirichlet function is discontinuous everywhere According to the definition of continuity, if f (x0) = LIM (x - > x0) f (x), the function is continuous at x0 For example, it is known that x0 belongs to Q. if it is not continuous, LIM (x - > x0) must not belong to Q. how to verify that LIM (x - > x0) does not belong to q?
20. Why can't Dirichlet higher numbers be expressed as limit functions of continuous functions