Multiple choice questions (3 points for each question, ***30 points)
1 and1in 1999, the national fiscal revenue reached1137.7 billion yuan, and the approximate value of retaining two significant figures by rounding method was () billion yuan.
(A) (B) (C) (D)
2. There are () integers * * * greater than–3.5 and less than 2.5.
6 (B)5 (C)4 (D)3
3. The corresponding points of known numbers on the number axis are on both sides of the origin, and the positions to the origin are equal; The number is reciprocal, so the value of is equal to ()
(A)2(B)-2(C) 1(D)- 1
4. If the product of two rational numbers is positive and the sum is positive, then these two rational numbers ().
(a) The signs are the same, and they are all negative numbers; (b) The signs are different, and the absolute value of positive numbers is greater than that of negative numbers.
(c) Positive numbers with the same sign and different signs (D), and the absolute value of negative numbers is greater than positive numbers.
5, in the following statement, the correct number is ()
(1) Any rational number can be represented by a point on the number axis.
(2) Every point on the number axis represents a rational number.
(3) The absolute value of any rational number cannot be negative.
(4) Every rational number has an inverse number.
a、 1 B、2 C、3 D、4
6. If the reciprocal of a number is greater than itself, then the number is ().
A, positive number b, negative number
C, integer d, rational number not equal to zero.
7, the following statement is correct ()
A. multiply several rational numbers. When there are odd factors, the product is negative;
B. multiply several rational numbers. When there are odd positive factors, the product is negative;
C, multiply several rational numbers, and when there are odd negative factors, the product is negative;
D, several rational numbers are multiplied, and when the product is negative, there are odd negative factors;
8, in the rational number, the absolute value is equal to its own number ().
A.1b.2c.3d. Infinite.
9, the following calculation is correct ()
A.-22 =-4b .-(-2)2 = 4c .(-3)2 = 6d .(- 1)3 = 1
10, if a
0 th century -2 nd century-2 nd century
Fill in the blanks: (2 points for each question, ***42 points)
1、。
2. Xiaoming and Xiaogang agreed on a new operation *: If both A and B are rational numbers, then a*b =. Xiaoming works out 2*5=-4, please help Xiaogang work out 2 *(5)=.
3. If, then =;
4. Integers greater than -2 and less than 3 are _ _ _ _ _ _ _ _ _ _ _ _,
5. The radix in (-3.2) 3 is _ _ _ _ _, and the sign of the result of power is _ _ _ _ _ _.
6. The sum of numbers A and B is -23.4, the number B is -8. 1, and A is greater than B.
7. Representing two numbers on the number axis, the number of is always greater than. (Fill in the blanks with "left" and "right")
8. Carefully observe and think about the laws with the following numbers: -2, 4, -8, 16, -32, 64. ............................... then fills in the following two spaces: (1) The seventh number is; (2) The nth number is.
9. If │-A │ = 5, then A = _ _ _ _ _ _
10, it is known that if (A and B are integers), then a+b=.
1 1. Write three rational numbers to satisfy: ① is negative; ② is an integer; ③ divisible by 2, 3 and 5. A: _ _ _ _ _ _.
12, the rational number represented by the point at 4.8 cm to the right of the origin on the number axis is 32, then the rational number represented by the point at 18 cm to the left of the number axis is _ _ _ _ _ _ _ _.
13, if known, then A is _ _ _ _ _ _ _ _; If it is known, then A is _ _ _ _ _ _ _.
14, calculation: = _ _ _ _ _ _.
15, known, then = _ _ _ _ _ _.
The approximate value 3. 142 is obtained by rounding the rational numbers in the range of 16, _ _ _ _ _ _ _ _ _ _.
17、:= 。
The absolute value of 18 and the number 5 is 5, which is itself; The absolute value of the number -5 is 5, which is its reciprocal; The above is derived from the theorem that the absolute value of a non-negative number is equal to itself and the absolute value of a non-positive number is equal to its opposite number. Judging from this sentence, the absolute value of positive number -a is _ _ _ _ _ _ _ _; Negative number-the absolute value of b is _ _ _ _ _ _ _ _; The absolute value of negative number 1+a is _ _ _ _ _, and the absolute value of positive number–a+1is _ _ _ _ _ _ _.
19, known |a|=3, |b|=5, a.
20. Observe the following equation, and what laws will you find:,,. . . Please use an equation with only one letter n(n is a positive integer) to express the law you found.
2 1, observe the following. . . Please use n(n≥ 1) to indicate the rule of your guess.
22, known, then _ _ _ _ _ _.
23, at that time, the result of simplification is
24, known as an integer, is even, so A is (odd, even).
25. As a result of simplification at that time.
Third, calculate the following questions (write down the key steps to solve the problem):
1、 2、
3、
4、(-8 1)÷2×(-)÷(- 16) 5、
6、 7、
Fourthly, we have learned that the sum of any two rational numbers is still rational, and mathematically, the set of rational numbers is closed to addition. Similarly, the set of rational numbers is closed for subtraction, multiplication and division (divisor is not 0). Please judge whether the integer set is closed for the four operations of addition, subtraction, multiplication and division. (4 points)
Answer with your conclusion:
If a, b and c are integers, and.
Answer: 1. 1，A2A3B4C5B6B7D8D9A 10D。
Two. 1 8,2, 16,3, 1 1,4,- 1,0, 1,2,5,-3.2,6,-7.2,7.
9,510, 109, 1 1, -30, -60, -90 12,-120, 13 Greater than or equal to 3. 14 15 and less than 3. 1425, 17, 18, -a, b,-1-a,-a+/kloc-.
22,-1, 23,, 24, odd, 25, -a-6
Three. 1, 24 2, - 1/5 3, -30 4, - 1 5, -47 6, 23 7, -96.
Fourth, addition, subtraction, multiplication, closure and non-closure.
Verb (abbreviation of verb) 2