1."Sum of X and Y" can be expressed as () by algebraic expression.
A.(x+y)B.x++yC.x+yD.x+y
2. Let n be an integer, and the even number in the following formula is ().
a . 2nb . 2n+ 1c . 2n- 1d . n+2
There is a piece of asbestos tile, each piece is 60 cm wide. When used to cover the roof, the width of every two adjacent overlapping parts is 10 cm, and the width of n(n is a positive integer) asbestos tiles is ().
A.60n nm cm B.50n nm cm C. (50n+10) cm D. (60n-10) cm.
4. In the following formulas ab, ab2+b+ 1, x2+x3-6, the polynomial has ().
A.2 B.3 C.4 D.5
5. In the following groups, () is the same project.
A.4x3y and-2xy3b. -4yx and 7xy
C.9xy and -3x2D.ab and bc
6. Xiao Wang designed a calculation program with a computer. Input and output data are as follows:
Enter … 12345…
output ...
Then, when the input data is 8, the output data is ().
Asian Development Bank.
7. Given a-7b=-2, the value of 4-2a+ 14b is ().
A.0B.2C.4D.8
8. If A=a3-2ab2+ 1 and B=a3+ab2-3a2b, then A+B= ().
a . 2 a3-3a B2-3a2b+ 1b . 2 a3+ab2-3a2b+ 1
c . 2 a3+ab2-3a2b+ 1d . 2 a3-ab2-3a2b+ 1
9. In math class, the teacher talked about the addition and subtraction of polynomials. After school, Xiaogang came home and took out his class notes. He carefully reviewed what the teacher said. He suddenly found a question X2+_ _ _ _ _ _+Y2 with ink on it, so one of the spaces was ().
A.-7xyB.7xyC.-xyD.xy
10. As shown in the figure, the polygon in Figure ① (the number of sides is 12) is "expanded" from an equilateral triangle, while the polygon in Figure ② is "expanded" from a square, …, and so on, and the number of sides of the polygon "expanded" from a regular N-sided shape is ().
a . n(n- 1)b . n(n+ 1)c .(n+ 1)(n- 1)d . N2+2
In the review, we should try our best to review and summarize all aspects of knowledge in a planned and step-by-step manner. The editing teacher will organize mid-term exercises for the seventh grade mathematics for the students, and I hope the students will adopt them! ! !
I. Multiple choice questions (10*3=30 points)
1. The following quantities with opposite meanings are (? )
A. won two games and lost three.
B. The profit is 30,000 yuan and the expenditure is 30,000 yuan.
C. The temperature rises by 3℃, and the temperature is -3℃
D Xiaoming goes east10m, and north10m.
2. According to statistics, by the end of 10 this year, the deposit balance of financial institutions in our city was about 1 193 billion yuan, which should be recorded as (? )
A.1193x109 Yuan B.0.1193x13 yuan.
C.1.193x10/yuan D.11.93x10/2 yuan.
3. The reciprocal of-2 is (? )
A.B.2C.﹣2D.
4. The result is (? )
A.8B。 4C.8D.4
5. The number of irrational numbers in is (? )
A.2 B.3 C.4 D.5
The square root of 6 is (? )
A.4B. 4C.2D. 2
7. The following statement is true (? )
A. the inverse number is 1, 0B. The number whose absolute value equals itself is 0.
C. the absolute value of irrational numbers must be positive. The arithmetic square root must be a positive number.
8. The following formula is correct (? )
A.B.C.(﹣4)﹣5=9D.﹣32=﹣9
9. In the following groups:
①-52 and (-5) 2; ② (-3) 2 and-32; ③-(-0.3) 5 and 0.35; ④0 100 and 0200; (5) (-1) 3 and (-1) 2,
Equality * * * has (? )
A. 1 pair B.2, pair C.3 and pair d.4.
10. Observe the following categories: 3=3, 32=9, 33=27, 34=8 1, 35=243, 36 = 729 ... Can you find any rules in the single digits with radix 3 as a power? According to the law you found, answer: the unit number of 320 14 is (? )
A. 1B.3C.7D.9
Fill in the blanks (this topic is ***6 small questions, with 4 points for each small question and 24 points for * * *).
1 1. If X represents a two-digit number and Y also represents a two-digit number, now you want to form a four-digit number with X and Y, and put X on the right side of Y, then this four-digit number is _ _ _ _ _ _ _ _.
12. Please write a quartic monomial with a coefficient of -7 _ _ _ _ _ _ _ and contain only the letters X and Y. 。
13.xa- 1y and -3x2yb+3 are similar terms, so a+3b = _ _ _ _ _ _ _.
14. (Lianyungang, Jiangsu) is a numerical converter as shown in the figure. If the input number is 3, the output number is _ _ _ _ _ _ _.
15. When Xiaolan subtracts x2-3x+5 from a polynomial, she mistakenly thinks that the addition of x2-3x+5 will get 5x2-2x+4, and the correct answer is _ _ _ _ _ _ _ _.
16. As shown in the figure, the following geometric bodies are arranged on the ground by small cubes with side length of 1 according to certain rules. If all the exposed surfaces are painted (the bottom surface is not painted), then there are only two painted cubes in the nth geometry * * * with _ _ _ _ _ _.
Third, answer the question (this is entitled ***4 small questions, ***46 points)
17.( 15 points) Calculation:
( 1)3c 3-2 C2+8c- 13c 3+2c-2 C2+3；
(2)8 x2-4(2 x2+3x- 1)；
(3)5x2-2(3y2-5x2)+(-4y2+7xy)。
18.( 12 points) Simplify before evaluating:
(1)(3a2-ab+7)-(5ab-4a2+7), where a=2 and b =；;
(2) 3 (ab-5b2+2a2)-(7ab+16a2-25b2), where |a- 1|+(b+ 1)2=0.
19.(9 points) Xiao Qiang and Liang Xiao simultaneously calculated an evaluation question: "When a=-3, find the value of the algebraic expression 7a2-[5a-(4a-1)+4a2]-(2a2-a+1)." Liang Xiao correctly got the result of 7.
20.( 10 point) At present, house prices have risen sharply, and the state has issued many policies for this, but some real estate developers are still unmoved and change their ways to raise prices. "Cosmos Real Estate Company" announced that in the first half of this year, land prices rose by 10%, building materials rose by 10%, and advertising and labor costs rose by 10%. If it is unreasonable, how much should the house price rise to protect the capital?
Reference answer
1 answer: d
2 answer: a
3 Answer: C Cuo: Because the width of every two adjacent overlapping parts is 10 cm, the width covered by n asbestos tiles is 60n-10 (n-1) = (50n+10) cm. So I chose C.
Answer: Dial B: ab2+b+ 1, x2+x3-6 is a polynomial, ***3, so choose B. 。
5 answer: b
Answer: C-click: Observing this numerical table, we can find that the output data is a fraction, the numerator is the same as the input data, and the denominator is the square of the numerator plus 1, so the output data is, so C.
7 Answer: D- dial: 4-2A+14B = 4-2 (A-7B) = 4-2× (-2) = 4+4 = 8. So choose D.
8 Answer: D- Dialing: A+B = (A3-2ab2+1)+(A3+ab2-3a2b) = A3-2ab2+1+A3+ab2-3a2b = 2a3-ab2-3a2b+/kloc-0.
Answer: c-click: =-x2+3xy-y2+x2-4xy+y2 =-x2-xy+y2. So one of the spaces is -xy, so choose C.
10 answer: B CuO: the number of sides of a polygon "expanded" from an equilateral triangle is 3×4= 12, the number of sides of a polygon "expanded" from a square is 4×5=20, and the number of sides of a polygon "expanded" from a regular pentagon is 5×6=30, from a regular hexagon.
1 1 answer: 100y+x tip: according to the meaning of the question, the four digits that meet the meaning of the question are 100y+x. Note: the y placed on the left should be multiplied by100.
12 answer: the answer is not unique, such as -7x2y2, -7x3y, -7xy3.
13 answer: -6
14 answer: 65-point dialing: if the input number is x, according to the program displayed by this numerical converter, the output number is (x2- 1)2+ 1. If x=3, it is calculated as 65.
15 answer: 3x2+4x-6 CuO: This polynomial is (5x2-2x+4)-(x2-3x+5) = 5x2-2x+4-x2+3x-5 = 4x2+x-1. So the correct answer is (4x2+x.
16 answer: (8n-4) Cuo: In the figure (1), there are only two 4=8× 1-4 color cubes * *, and in the figure (2), there are only two 12 color cubes * *.
17 solution: (1) Original formula = 3c3-13c3-2c2-2c2+8c+2c+3 =-10c3-4c2+10c+3;
(2) The original formula = 8x2-8x2-12x+4 =-12x+4;
(3) The original formula =5x2-6y2+ 10x2-4y2+7xy.
=(5+ 10)x2+(-6-4)y2+7xy
= 15x2- 10y2+7xy。
18 solution: (1) Original formula = 3A2-AB+7-5A B+4A2-7 = 7A2-6A B. When a=2 and b=, the original formula =28-4=24.
(2) because |a- 1|+(b+ 1)2=0, and |a- 1|≥0 and (b+ 1)2≥0, a- 1=0.
The original formula = 3ab-15b2+6a2-7ab-16a2+25b2 =-10a2+10b2-4ab.
When a= 1 and b=- 1, the original formula =-10/2+10 × (-1) 2-4×1.
The solution of 19: the original formula = 7a2-(5a-4a+1+4a2)-(2a2-a+1) = 7a2-4a2-a-1= a2.
From the simplified results, as long as the value of a is opposite, the calculation results are always equal. Therefore, when a=3 or a=-3, there is a2-2=9-2=7. Therefore, Xiao Qiang's calculation result is correct, but his problem-solving process is wrong.
On the surface, what the real estate agent said seems very reasonable: since the house price is composed of three parts, each part will increase by 10%, and of course the total price will also increase by 30%. Actually, this statement is wrong.
In fact, if the total house price is W yuan, and the land price, building materials, advertising and labor costs are A yuan, B yuan and C yuan respectively, then W = A+B+C B+C. Each part will increase by 65,438+00%. Then the total price becomes a (1+10%)+b (1+10%)+c (1+10%) = (a+b+c).