The seventh grade volume is synchronized with mathematics. The reference answer to "New Curriculum Classroom Synchronization Exercise Book Mathematics (East China Edition Seventh Grade Volume)" Chapter 6 One-dimensional Equation 6. 1 From Practical Problems to Equation 1, 1. D2。 x =-62。 2x- 15 = 253。 x = 3 ( 12-x) III。 1. solution: if the production and operation water consumption is x billion cubic meters, the household water consumption is (58-x) billion cubic meters, which can be listed as an equation. Then the countable equation is: 4x+3(5-x)= 173. Solution: Let the number of students in the original extracurricular mathematics group be X, then the countable equation is: 6.2 Solve the linear equation of one yuan (1), 1. D 2。 C 3。 a， 1.X. X= 2. 10 3。 x=5 III， 1。 X = 72。 X = 43。 X = 4。 X = 5。 X = 36。 Y = 6.2 Solve the linear equation (II) I, 1. B2。 1.X =-5，y = 3 ^ 2。 3.-3 Three, 1. ( 1)X =(2)X =-2(3)X =(4)X =-4(5)X =(6)。 Get: 9x-5 = 8x+2. Solved: x=7 (2)48 people 3. (1) x =-7 (2) x =-3 6.2 Solve the linear equation of one variable (3) 1. 1.C2.D3.B. 1。 1 2.3. 10 three, 1. ( 1)X = 3(2)X = 7(3)X =– 1(4)X =(5)X . X =-3 3。 3 yuan 6.2 solves the unary linear equation (4) 1, 1. B 2。 B 3。 D 2， 1。 5 2.3.4. 15 III. 1. ( 1) Y = (2) Y = 6 (3) (4) x= 2。 Solve equation 3(5x-6)=3-20x to get x=, and substitute X = into equation A-X to get a =-8. When a=-8, Equation 3(5x-6)=3-20x has the same solution as Equation a- x=2a+ 10x. 3. Get a solution: x = 9 6.2 Solve the linear equation (5) I and 65438+. 8 3.2x+1 0 = 6x+5 4.15.160 yuan 3,1. Suppose person X goes to A, and according to the meaning of the question, 27+x=2[ 19+(20-x)] is obtained. Get1.2× 6+2 (x-6) =1.4x. Solve x=8. So 1.4x= 1 1.2 (yuan). When the number of students is X, the fees charged by the two travel agencies are the same. According to 240+120 x =144 (x+1), x = 4 is obtained. 6.3 Practice and exploration (1), 1.b2.b3.a2, 1.36 2. 270 three. 1. Let the digits of the original two digits be x, which means 65438+700-x+1-x =10 (11-x)+x+63. Get 30x+50(700-x)= 29000. Get x=300, then 700-x=700-300=400 people. Then sell 300 children's tickets. Sold 400 adult tickets. 6.3 Practice and Exploration (II) I. 1. A 2。 C 3。 C 2, 1. X+X+ 1 = x2.23.75% 3.2045 III. 660. 5(x+2)+4(2x+2)=200 gives x= 14. Then Party A will process 16 pieces per hour, and Party B will process 14 pieces per hour. 2. Suppose Mr. Wang needs to borrow X yuan from the housing provident fund. 3.6% x+4.77%(250000-x)= 10 170。 The solution is x= 150000. Then Mr. Wang needs to borrow 150000 yuan from the housing accumulation fund and 100000 yuan from the ordinary housing loan. Get the solution x = 1.4 hours. Chapter 7 Binary linear equations 7. 1 Binary linear equations and their solutions I, 1. C 2。 C 3。 b， 1.2.53.3， 1。 Let a have x books. B there were y books, according to the meaning of the title, there were two. Each big piece contains X cans, and each small piece contains Y cans. According to the meaning of the title, there are three. There are x cars and y students. According to the meaning of the question, 7.2 Solutions of binary linear equations (1), 1. D 2。 B 3。 B 2， 1。 2, omit 3. 20 3, 1.2.3.4.7.2 Solutions of binary linear equations (2), 1. D 2。 C 3。 One second, 1. , 2. 18, 12 3. Third, 1. 2.3.4.4. The planting areas of vegetables A and B are X and Y mu respectively. According to the meaning of the problem, we can get the solution of 7.2 binary linear equations for solving this equation group (3) 1. 1.b2.a3.b4.c 2。 1.2.9 3. 180.20 3. 1.2.3.4. Let the gold medal and silver medal be X and Y respectively, then the bronze medal is (y+7). According to the meaning of the problem, we can solve this system of equations. Therefore, y+7 = 2 1+7 = 28. 7.2 Solutions of Binary Linear Equations (4) 1. 1.D 2。 C 3。 B 2。 1.2.3, 3.- 13 Third, 1. 1.2.3.4.5.6 Fourthly, Xiao Ming has booked B-class and C-class tickets, X and Y respectively. According to the meaning of the problem, if we want to get the solution of this equation group, we have to get 7.2 solutions of the binary linear equation group (5) 1. 1.D 2。 D 3。 A 2。 1.24 2.6 3.28 yuan, 20 yuan III, 1. (1) The number of days (days) for finishing and rough machining of processing projects, and the profit (yuan) is 6,000 x 8,000 y (2) is obtained from (1): The solution is ∴ A: This batch of vegetables is 70 tons in total. 2. Set a basketball for each yuan. According to the meaning of the question, every dollar of B-type basketball can be solved. 3. Assuming that it takes X yuan and Y yuan to buy Class A goods of 1 and Class B goods of 1 before discount, this equation group can be solved according to the meaning of the question. Therefore, 50× 16+50×4-960=40 (yuan). 7.3 Practice and Exploration (1) 1. 1.C 2。 D 3。 A 2。 1.722.3.3438+0.4 million. According to the meaning of the problem, we can get a solution. 2. If the sandbag falls in Area A, we can score. According to the meaning of the problem, we can get a solution. A: Xiao Min's total score of four times is 30 points. 3.( 1) If the price of washing machine A is X yuan and that of washing machine B is Y yuan, then we can get a solution of equation (2) according to the meaning of the question. Actual amount paid by Xiao Wang: (Yuan). 7.3 Practice and Exploration (II) I. 1. A2.A3.D II， 1.55m/min，45m/min 2。 20, 18 3.2, 1 3. "No.1 seedless" litchi harvested y kilograms. According to the meaning of the problem, we can solve this system of equations. 2. Suppose a one-yuan coin gram and a five-yuan coin gram. According to the meaning of the question, we can get the solution: 3. Set the original plan to produce x tons of wheat and y tons of corn. According to the meaning of the question, the solution is10× (1+12%) =1.2 (ton), 8× (1+10%). >; > ; > 2.2x+3 3; (2)a+7 < 0； (3) 2+ 2≥0; (4)≤-2; (5)∣ -4∣≥ ; (6) The set of all solutions of-20, such as x= 1 is also the inequality 3-x.3.1.x > 3; 2.x ≥-2 3。 x < 4。 x > 5 4。 x≥- 1。 Sketch 5. (1) (2) (3) 8.2 Solve a linear inequality (3) 1. 1.C 2。 A 2。 1.x≤-3 2.x≤-3.k > 2 3， 1。 ( 1)x >-2(2)x ≤- 3(3)x ≥- 1(4)x 12。 When 0 < x ≤ 12, the solution of 200×12 < 0.85 (200×12+50x) is x >, so the integer solution of < x ≤ 12 is 9,12. 12. Therefore, it is more favorable to buy more than 9 dining chairs and less than 32 dining chairs and go to Mall A.. 8.3 Inequality Group (I), 1. A 2。 b， 1。 X >- 1 2。 - 1 < X. 1。 (1) x ≥ 6 (2)1< x < 3 (4 ≤ x <10 (4) x > 2 (omitted) 2. If there are x children in the kindergarten, there are 3x+59 toys in this batch. The solution is 30.5≤x≤3 1.5, because x is an integer, so x=3 1, 3x+59 = 3× 31+59 =152 (pieces) 8.3 linear inequality (ii) i. < X. 1。 (1) 3 < x < 5 (2)-2 ≤ x < 3)-2 ≤ x < 5 (4) x ≥13 (omitted) 2× 3+2.5x < 204× 3+2x. So x=5 (yuan) (short answer) 3. The positive integer solution of -2 < x ≤ 3 is 1, 2,34. Assuming the remaining funds, you can also buy a schoolbag and a cultural shirt for each student in X Mingshan Primary School, and you can get 350 ≤ 1800-( 18+30) according to the meaning of the question. So x=30.5. (1) This shipment is 66 tons. (2) 2 vehicles with a load of 5 tons and 7 vehicles with a load of 8 tons. Chapter 9 Polygon 9. 1 triangle (1) I, 1. C2。 C2， 1。 2.3. 12, 1.8 at right angles; △ABC, △FDC and △ADC are acute triangles; △ABD and△△△ AFC are obtuse triangles; △AEF, △AEC and △BEC are right triangles. 2.( 1) omitted (2) Three midlines intersect at one point, and the ratio of two line segments divided by the intersection point is 1:2. 3. Inconsistent, because the sum of the internal angles of the triangle should be equal to 180.4. ∠ A = 95 ∠ B = 52.5 ∠ C = 32.5 9. 1 triangle (2), 1 . C2 . B _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _。 (2) 20,40 (3) 25,35 2. 1 65 3.20 4.20 5.3: 2:13,1. ∠BDC should be 2 1+32+90 = 143. 1.D 2。 A two, 1. 12cm 2. 3 pieces 3.5