Winter vacation homework answers 202 1 math in grade seven.
Rich graphical world (1) solutions:
1、D； 2、B； 3、B、D； 4、20; 5、B； 6. Omission
Rich graphic world (2) Solutions:
1、D； 2、A； 3、D； 4、D； 5、C； 6、B； 7, at least 9, at most12;
8. Circle along the length: 36; Make a circle 48 along the width;
Solution and operation of rational number
1.C2 d 3 . B4 . b . 5 . b . 6 . C7 . D8 . C9 . d 10。 C 1 1。 B 12。 D
13.-314.15.-3.516. Negative number 17. 18.26, 27.5, 24.5;
19.( 1)-8(2)(3)40(4)-3; 20. Omit 2 1. -2c； 22.3; 23. 1
24. Solution: (1) Let the upstream be the positive direction.
∵5+5-4-4.5= 1+0.5= 1.5,
At this time, the survey team is at 1.5km upstream of the starting point.
(2) The distance is 1.5km,
(3) The water conservancy survey team will walk 20km.
25.( 1) Friday (2)35 vehicles (3)-27 vehicles, insufficient, 27 vehicles less.
26. Solution: (1)∵ Not lower than 500 yuan, and 10% discount for 500 yuan.
If you make a one-time shopping in this mall, 500 yuan actually pays 450 yuan.
(2) purchase a (a > 500) yuan items.
According to the meaning of the question, the actual payment =500×0.9+0.8(a-500)=(0.8a+50) yuan.
(3) When the shopping cost is 138 yuan. ∵ 138
I spent 482 yuan on shopping. ∫0.8a+50 = 482，a = 540540-482=58
∴ These two purchases cost 138 yuan and 482 yuan respectively, saving 58 yuan.
He can save more. The plan is: we can buy them together. The reason is: when you buy together,
∫ 138+540 = 678, while 500×0.9+(678-500)×0.8=592.4,
∴678-592.4=85.6. So it will be cheaper to buy together, saving 85.6 yuan.
The solution of algebraic expression plus or minus one
I 1，A2，A3，D4，C5，B6，C
Second, 1, (1) a+b-c-d; (2)a-b-c+d； (3)_ a+b+ c-d； (4)-a+b-c。
2、a=__ 1__，b=_3_
3 、( 1)2n(2)700
4、n(n+2)=n2+2n
Third, 1, (1); (2)
(3) The original formula =2-9x-2x2, 1 1.
2 、( 1)S = 32(2)S = 3200；
3、4
4.( 1) A: (0.2x+500) yuan; B: 0.4x yuan;
(2) A: 980 yuan; B: 960 yuan; It is more cost-effective to choose printing house B;
(3) A: 7500, B: 5000; A printing factory printed more than 2500 copies.
Algebraic expression addition and subtraction solution II
I./kloc-0 1A2B3C4C5D6D
Second, 1,-+
2 、( 1)n- 1，n，n+ 1(2)2n-4，2n-2，2n
3 、-2b4527689
three
1 、( 1)3( 1-2ab 2)-2(a2 b-4ab 2)
(2)x-(3x-2)+(2x-3)；
Solution: Original formula =3-6ab2-2a2b+8ab2 Solution: Original formula =x-3x+2+2x-3.
=3-6ab2+8ab2-2a2b=x-3x+2x+2-3
= 3+(-6ab 2+8ab 2)-2a2b =(x-3x+2x)+(2-3)
=3+2ab2-2a2b=- 1
(3)3a2-2(2a2+a)+2(a2-3a), where a =-2;
Solution: Original formula =3a2-4a2-2a+2a2-6a
=3a2-4a2+2a2-2a-6a
=(3a2-4a2+2a2)+(-2a-6a)
=a2-8a
Substituting a=-2, the original formula is =(-2)2-8×(-2).
=4+ 16
=20
2. Nitrogen
3、 10y+x 10x+y
Solution of basic plane figure
Basic plane figure (1):
1、B； 2、D； 3、C； 4, 5 questions; 6、60′,2520″,30 15′36〞;
7, 5cm or15 cm; 8、 15.5 ;
9.( 1) is equal.
10, (1) ∠ AOC =130 and A, O and B are on the same line.
∴∠BOD= 180 - 130 =50
∫OD is the bisector of∝∠ ∝∠AOC.
∴∠COD=∠AOC=× 130 =65
Oe is the bisector of ∠BOC.
∴∠COE=∠BOD=×50 =25
∴∠DOE=∠COD+∠COE=65+25 =90
(2)DOE∠ degree remains 90. The reason for this is the following：
From (1): ∠COD=∠AOC, ∠COE=∠AOC.
∴∠DOE=∠COD+∠COE=∠AOC+∠BOD
=(∠AOC+∠BOD)
=× 180 =90
Basic plane graphics (2):
1、A； 2、A； 3、C； 4、A；
5，(n-3)，(n-2)； 6, 15; 7, 75 degrees; 8, 2; Two points determine a straight line; 9、 1cm；
10 、( 1)≈∠AOE = 100，
∠∠EOG is folded from ∠BOG.
∴∠EOG=∠BOG
∴∠eog+∠bog+∠aoe=2∠eog+∠aoe= 180
∴∠eog=( 180-∠AOE)=×( 180- 100)= 40
(2)2∠EOG+∠AOE = 180
∴2y+x= 180
1 1、AC = a b+BC = 6+4 = 10； AO = AB =× 10 = 5； OB=AB-AO=6-5= 1
The Solution of "One-variable Linear Equation 1"
First, multiple-choice questions: CDAABD
2，7，n= 1，m = 1； 8、40; 9、24; 10、a=7
Third, answer questions:
1 1、X = 1 1； 12、X =-3；
13, solution: he began to save x yuan.
( 1+2.7%×6)x=58 10
Solution: x=5000
14, solution: suppose there are x male workers, then there are 70-x female workers.
( 1- 10%)x=70-x+6
The solution is X=40.
15, assuming the uphill speed is xkm per hour, then the downhill speed is 1.5xkm per hour.
According to the meaning of the question, x+ 1=× 1.5x,
Solution: x=4
Answer: uphill speed is 4km, downhill speed is 6km, and one-way street is 5km.
Solution of "One-variable Linear Equation 2"
First, multiple-choice questions: DCCCBC
Second, multiple-choice questions: 7, m =101; 8、- 13; 9. 1000 yuan; 10, 2km/h
Third, the calculation questions: 1 1, x = 43 12, x = 2；;
13. There are x students in the whole school.
X-21x-41x-71x = 3 solution: x=28.
14, and the annual interest rate of the bond is X.
5000+5000×x×2( 1-20%)= 5400
X=5%
So the annual interest rate of bonds is 5%
15. It takes my brother x hours to catch up with my brother and mother.
The equation is 6X=2+2X.
Solution: X=0.5 hours. 10x =10x0.5 = 5km.
A puppy ran 5 kilometers.
Answers to "Data Collection and Processing"
1, (1) sampling survey (2) general survey (3) sampling survey (4) sampling survey.
(5) Census (6) Sampling survey (7) Census
2、D
3. Generally speaking, it is all the achievements of 9068 junior high school graduates in a city this year.
Individuals are the results of the entrance examination for each junior high school graduate;
The sample is the entrance examination scores of 300 candidates drawn from it;
The sample size is 300.
4, broken line statistics
5. yes. You can see the percentage of each part more intuitively.
672 degrees
7、C
8、D
9.( 1) Teacher Zhang's sample size = (person)
(2) Add Figure A and Figure B as follows:
(3) The number of students enrolled in vocational high schools in the whole year =225.
10 ,( 1)x = 12，y= 1，m=0.24n=0.02
(2) The degree of central angle of equal sector =36 degrees.
(3) Equal number =76.
Equal number of people =92
Winter vacation study plan template
First of all, the specific plan is as follows
(1) insist on going to bed early and getting up early. Get up at seven o'clock in the morning to wash and tidy up the house, go to bed at ten o'clock in the evening on time, and spend half an hour cooking a breakfast for your family that is not necessarily rich and delicious, but must be full of love;
(2) After breakfast, take ten minutes to wash dishes, take out Chinese and English textbooks at 7: 40 and read aloud for 20 minutes; (read in Chinese and English in turn);
(3) Starting at 8 o'clock, complete all the topics in the last class of the winter vacation exercise book, and time it for one and a half hours;
(4)9:30-9:40, rest 10 minutes, drink water and see the distant scenery;
(5) Starting at 9: 40, complete all the topics in one subject in turn, and time it for one and a half hours;
(6) 1 1: 10 helps mom and dad make lunch;
(7)11:10-12: 30 This time period includes eating and washing dishes;
(8) Take a nap at12: 30, and get up at 13: 50;
(9) 14:00, finish two test papers regularly (according to this final exam, buy some counseling materials and test questions of the worst subjects);
(10) Correct the test paper by yourself according to the answers, write the analysis of the wrong questions next to the wrong questions, prepare the correction book, write the wrong questions on the correction book, cover the test paper and answer it again;
(1 1) 17: 30 to help mom and dad cook dinner;
(12)17: 30—19: 00 This time period includes eating, washing dishes and resting;
(13) at 7: 00 pm, spend an hour and a half writing a diary (if it is Sunday, write a weekly diary directly) and accumulate a good article;
(1 4) Watch TV at 20: 30-2 1: 30/hour or play computer games1hour;
(15) 2 1: 30 Take a shower and brush your teeth, and go to bed at 22: 00 on time!
Second, self-punishment
(1) If the life plan is not completed, cancel the entertainment time of the day and copy a paragraph;
(2) If the study plan cannot be completed on time and in quantity, the entertainment time of the day will be cancelled and a fine of 15 push-ups will be imposed;
(3) Special treatment in special circumstances, please ask mom and dad to supervise;
Effective learning skills in junior high school
The study of all subjects should be systematic.
During primary school, students learn some relatively simple basic contents, and all subjects are relatively simple. But after junior high school, the learning content has changed a lot. With the increase of physics and chemistry, the academic burden of junior high school students has greatly increased. In addition, junior high school teachers attach importance to cultivating junior high school students' thinking methods and abilities. At this stage, junior high school students should change their learning style and be more inclined to use knowledge.
Learn to attend classes and improve classroom efficiency
Listening to classes is something that every junior high school student must learn, and it is very important for junior high school students' learning progress. The learning efficiency of a class directly determines the performance of junior high school students. Junior high school students must "move" themselves in class, not physically, but mentally. Don't skip the number, take questions when listening to the class, and follow the teacher's ideas.
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