1. The following algebraic writing specification is ()
a . a×2 b . 1 a . c .(5÷3)a . d . 2 a2
2. If the length of a rectangle is a and the width is b, then the area of this rectangle is ().
ab C.ab D.2(a+b)
3. A two-digit number, where ten digits are A and one digit is B, then this two-digit number is ()
10a+b d 10b+a
4. The following statement is true ()
A.0 and x are not monomials. The coefficient of b-
The coefficient of C.x2y is 0 d, and the degree of -22x2 is 2.
5. When a= 1, the value of | a-3 | is ().
a . 4 B- 4 c . 2d-2
6. It is known that 25x6y and 5x2my are similar terms, and the value of m is ().
A.2 B.3 C.4 D.2 or 3
7. The result of merging similar items-2x2y+5x2y is ().
7x2y C.3x2y D.7x2y
8. The following brackets are removed, and the correct one is ()
A.-(a+b)=-a-b b .(3x-2)=-3x-2
c . a2-(2a- 1)= a2-2a- 1d . x-2(y-z)= x-2y+z
9. Let M-N= 2a-3b and n =-2a-3b, then M-N= ().
A.4a-6b B.4？ c-6b d . 4a+6b
10. Both trains are from A to B. It is known that the speed of A train is X km/h and that of B train is Y km/h. After 3 o'clock, B train is 5 km away from B train, at which time A train is () km away from B train.
a . 3(-x+y)-5 b . 3(x+y)-5 c . 3(-x+y)+5d . 3(x+y)+5
Fill in the blanks (4 points for each small question, 24 points for * * *)
1 1. Xiaoying is n years old this year, Xiaoying was years old last year, and Xiaoying was years old six years later.
12. The single factor is, and the number is.
13.5 consecutive positive integers, and the middle number is n, then the sum of these five numbers is
The reciprocal of 14.-2a+ 1 is.
15.9,11,13, ..., the number 10 is, and the number n is.
16. It is known that the sum of ten digits and single digits of a two-digit number is 13. Let the unit number be a, and switch the ten digits with the unit number to get a new two-digit number.
Iii. Answering questions (***66 points)
17.(6 points) Simplify the following categories:
( 1)x-y+5x-4y(2)-2x-(3x- 1)
(3)(m-2n)-2(-2n+3m)(4)-2(xy-3 y2)-
18.(6 points) As shown on the right, it is a numerical converter, which operates according to the above operation mode, and the obtained values are filled in the table below.
Fill in the form:
Enter x-2- 1 0 1 2.
output
19.(6 points) It is known that A = x2-5x and B = x2- 10x+5.
(1) find a-2b; (2) Find the value of 2a-b when x =-.
20.(8 points) Given that one side of a triangle is m+n, the other side is m-3 longer than this side, and the third side is 2n-m, find the perimeter of this triangle.
2 1.(8 points) Given x2-xy = 60 and xy-y2 = 40, find the values of the algebraic expressions x2-y2 and x2-2xy+y2.
22.( 10) Mobile companies have opened two kinds of communication services:
① GSM users pay 10 yuan every month, and then pay 0.2 yuan per minute for calls.
② The users of "Autoexpress" don't pay the monthly fee, but pay the 0.4 yuan phone bill for every minute of the call.
(1) According to the calculation of 2 minutes a month, please write down the fees that customers should pay under the two charging methods.
(2) What kind of mobile communication do you think is appropriate for a user to talk for 300 minutes a month?
23.( 10) Use an algebraic expression with letters to represent the area of the shaded part in the figure.
24.( 12) There is such a problem: "When A = 0.35 and B = 0.28, more is required.
The value of formula 7a3-3 (2a3b-a2b-a3)+(6a3b-3a2b)-(10a3-3). "When Xiao Min did the problem, she mistakenly copied A = 0.35 and B =-0.28 into A =-0.35 and 6 = 0.28, but she made the result. Please explain the reason.
Reference answer:
1.D 2。 C 3。 C 4 explosive D 5。 C 6。 B 7。 C8.A 9。 B 10。 C 1 1。 (n- 1) (n+6) 12。
2 13.5n 14.2 a- 1 15. 15 27 2n+7 16。 ( 13-a)+ 10a
17.( 1)6x-5y(2)-5x+ 1(3)-5m+2n(4)4 y2+xy+x2
18.- 15,-9,-3,3,9
19.( 1)A-2B = x2-5x-2(x2- 10x+5)=-x2+ 15x- 10。
(2)2A-B = 2(x2-5x)-(x2- 10x+5)= x2-5。
When 2 =-, 2a-b = (-) 2-5 =-4.
20.(m+n)+(m+n+m-3)+(2n-m)=2m+4n-3。
2 1 . x2-y2 =(x2-xy)+(xy-y2)= 100。 x2-2xy+y2=(x2-xy)-(xy-y2)=20。
22.( 1) The expression of fees payable by customers of "Global Connect" is 0.2x+ 10 yuan; The payable expenses of "Kuaijietong" customers are expressed as 0.4x yuan.
(2) When x=300, the fees payable by "Global Connect" customers are 70 yuan; The fee payable by the customer of "Kuaijietong" is 120 yuan.
So we choose GSM mobile communication service.
23. the area of the shaded part is a+b+c 24. The result of simplification of the original formula is 3. Regardless of the values of a and b.