The addition and subtraction level test of algebraic expression in the first grade of mathematics 1. Multiple choice questions (3 points for each question, ***24 points).
1. The correct statement is ().
A. it is not an algebraic expression; B. the number of times is; C. and are similar projects; This is a monomial.
2.ab minus equals ().
A.； b； c； D.
3. The following equation is not equal to the value of a-b-c ().
a . a-(b+ c)b . a-(b-c)c .(a-b)+(-c)d .(b-a)
4. Merge 2 (x+y)-3 (x-y)-4 (x+y)+5 (x-y)-3 (x-y) into ().
A.-3x-y b .-2(x+y)c .-x+y d .-2(x+y)-(x-y)
5. If -4x2y and -23xmyn are similar terms, the values of m and n are () respectively.
A.m=2，n= 1 B.m=2，n=0 C.m=4，n= 1 D.m=4，n=0
6. Two items in the following two groups belong to the same category ().
A.x2y and-xy3; B.-8a2b and 5a2cC. pq and-qp; D. 19abc and -28ab
7. In the following categories, the correct bracket is ().
a . x2-(2y-x+z)= x2-2 y2-x+z b . 3a-[6a-(4a- 1)]= 3a-6a-4a+ 1
c . 2a+(-6x+4y-2)= 2a-6x+4y-2d .-(2 x2-y)+(z- 1)=-2 x2-y-z- 1
8. If the polynomial is known and A+B+C=0, then C is ().
(A) (B) (C) (D) Fill in the blanks (3 points for each question, ***24 points)
1. Please write two similar projects at will:,;
2. Given that x+y=3, the value of 7-2x-2y is;
3. If sum is similar, then m =；; n =；
4. When is 2y? When x=5, =;
5. Add -3+x-2x2 to a polynomial to get x2- 1, then this polynomial is;
6. In the algebraic expression -x2+8x-5+ x2+6x+2, the sum of -x2 is similar, the sum of 8x is similar, and the sum of 2 is similar.
7. Assuming that and are similar terms, the value of 5m+3n is.
8. Write an algebraic expression containing at least three terms, and the result of merging similar terms is three. Solve the problem (***32 points).
1. Calculation:
( 1)
(2)(3x2-xy-2y2)？ 2(x2+xy？ 2 y2)
2. Simplify first, then evaluate:
, among which,
3. Multiply a polynomial twice to get this polynomial.
4. It is known that m, x and y satisfy (1) and (2), and they are similar terms. Find the value of algebraic expression:.
Four, broaden the exploration (***20 points)
1.( 1) If +(b-2)2=0, A=3a2-6ab+b2, and B=-a2-5, find the value of A-B. 。
(2) Try to explain: No matter what values X and Y take, algebraic expressions
The value of (x3+3x2y-5xy+6y3)+(y3+2xy2+x2y-2x3)-(4x2y-x3-3xy2+7y3) is constant.
2. The original length of the spring is 8 cm. When the spring is pulled by F (F is within a certain range), the length of the spring is expressed by L, and the measured data are as follows:
Tension F/ kg 1 2 3 4?
The length of the spring is l/cm 8+0.58+1.08+1.58+2.0?
(1) Write the formula that the tension f represents the spring length l;
(2) If an object weighing 8 kilograms is suspended, what is the length of the spring?
(3) Multiple objects need to be suspended, and the spring length is 13cm?
Improve one's ability and surpass oneself.
1. In order to save water, a city stipulates that the monthly standard water consumption of a family of three is 15 cubic meters, and increases the excess water fee. Suppose the excess water fee is
1.5 yuan /m3, 3 yuan /m3 for excess water fee.
(1) Please use algebraic expressions to express the water charges payable for standard water consumption and water consumption exceeding the standard;
(2) If this family uses 20 cubic meters of water a month, how much water fee will it pay this month?
2. Miss Li gave the students a question: When a=0.35 and b= -0.28,
After the question was asked, Xiao Cong said: The conditions given by the teacher, a=0.35, b= -0.28, are redundant. Xiao Ming said:? If you don't give these two conditions, you can't get the result, so it's not redundant. Which one do you think makes sense? Why?
Answer 1: 1. b； 2.c； 3.b； 4.d； 5.a； 6.c； 7.c； 8.B
Second, 1. Such as 5x2yz3,12x2yz3; 2. 1; 3.m=2，n = 1；
4.45; 5 . x2-x+2； 6.x2； +6x； -5; 7. 13; 8. There are many algebraic expressions written, such as or.
Third, 1. ( 1)-6x 3+7； (2)x2-3xy+2 y2；
2. Simplification: when x=2 and y= 1, the original formula =-1;
3.- 13 x2-5x+5；
5.x =5，y =2，m = 0； Original formula = 44
Fourth, 1. (1) solution: ∫A = 3 a2-6ab+B2, B=-a2-5,? A-B =(3 a2-6ab+B2)-(-a2-5)= 4 a2-6ab+B2+5。
∫+(b-2)2 = 0，？ A-B=4？ 12-6? 1? 2+22+5= 1.
(2) The simplified result of the original formula does not contain the letters X and Y, that is, the original formula =0. No matter what values X and Y take, the value of the original formula is constant 0.
2. Solution: (1) The formula of pulling force f for spring length L is L = 8+0.5f. 。
(2) when F = 8kg, l=8+0.5? 8= 12 (cm). When an object weighing 8 kg is suspended, the length of the spring is 12 cm.
(3) When l = 13cm, there is 8+0.5f = 13cm. F= 10 (kg). When an object weighing 10 kg is suspended, the length of the spring is 13 cm.
Improve one's ability and surpass oneself.
1.( 1) The water fee standard is: 1.5a (0 15).
(2)37.5