Multiple choice questions in mathematics

First, multiple-choice questions.

1. Among the following logarithms, the opposite number is (b).

A.-6 and -(+6) B. -(-7) and +(-7) C. -(+2) and +(+2.2) D.- 1/3 and -(-2/3)

2. Move point A on the number axis to represent the number -2, move point A to the left by 8 unit lengths to reach point B, and then move point B to the right by 5 unit lengths to reach point C, then the number represented by point C is (D).

A.3 B. 1 C. 1 or -5 D.-5

3. The following groups of rational number size comparison, the error is (c).

A.0 >- 1b。 -2 < 3c。 -3/4

4. The following statements: ① there is the smallest natural number, ② there is the smallest positive rational number, ③27/9 is not a fraction, but an integer, ④ the number with the smallest absolute value is 0, ⑤ the absolute value is equal to its own number only 0, ⑤ the reciprocal is equal to its own number only 1, ⑦-a must represent a negative number, and the correct number is (b).

A.2 B.3 C.4 D.5

5. The following statement is correct (c).

A Approximation 1.70 has the same accuracy as approximation 1.7.

B the approximate value 500 has the same accuracy as the approximate value 500.

C. The approximate value of 4.70× 10 is a number accurate to hundreds, and it has three significant figures, namely 4. 7.0.

D. The approximate value of 24.30 is a number accurate to the tenth place, and it has three significant figures, namely 2. 4.3.

6. The correct one in the following statement is (c).

A. if ab > 0, then a > 0 and b > 0.

B. if buy x buy = buy y buy, then x = y.

C. if ab < 0, a+b < 0, a > b, a < 0, b > 0.

D. if m+n < 0 and Mn < 0, then m < 0 and n < 0.

Second, fill in the blanks.

The absolute value of 1 -5/3 is (5/3), and the reciprocal of-1 2/3 is (-3/5).

2. The distance on the number axis represents the number-1, and the number represented by three points of unit length is (-4 or 2).

3. Observe the following column numbers and explore their laws. If-1, 1/2,-1/3, 1/4,-1/5, ... then this number is (). The number 20 13 is (-1/20 13).

4. A new operation "*" is defined. When a > b, a * b = 3ab+a-b+2; When a is less than or equal to b, a*b=-a+2b- 1, such as 3 * 2 = 3× 3× 2+3-2 = 2 = 26438+0.

5. If the quadratic is 9, ? b? = 1, and ? b-a ? =a-b, then b-a=(-2 or -4).

3. Fill in the following numbers in the corresponding brackets representing the set.

32, -8 2/3,-15, -3. 14, 22/7, -4/5,-18%, 0, -5.2 cycles, -2

(1) Integer:-15,0,-(-2) ...

(2) Negative scores: -8 2/3, -3. 14,-18%, -5.2 cycles …

(3) Non-negative rational numbers: 22/7, l -4/5 l, 0, -(-2) …

Fourth, answer questions.

1. An overhaul team takes an overhaul car to overhaul along the railway, and the regulations are positive to the east and negative to the west. The starting point record of the motorcade is 0. When the overhaul is completed on a certain day, the trip record (unit: km) is as follows:+10, -2, -3,-1, -9, -3.

(1) How far is the maintenance team from the starting point when we call it a day? East or west?

(2) Let the maintenance vehicle consume 2.8L oil per kilometer, and find out how much L oil is consumed from the start to the manual operation.

Solution: (1):+ 10+(-2)+3,+(-1)+9-3+2-2+1+3-4+6 = 30.

So when we call it a day, it's 32 kilometers away from the starting point, on the east side of the starting point.

(2) 10+2+3+ 1+9+3+2+2+ 1 1+3+4+6=56

56x2.8 =156.8L.

2. It is known that the power of è a-4è+(b+1.5) is 0, cD =5/2, and D b-cD = -(b-c).

(1) Find A, B and C that meet the requirements;

(2) Find the value of A-B+C. 。

Solution:

( 1)a-4=0，b+ 1.5=0。

The solution is a=4 and b=- 1.5.