China. com reported the answers about our math page 20 10-20 1 1 The second semester newspaper explained the answers in detail.
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Mathematics page%% 20 1 0 ~ 201academic year seventh grade people's education edition ● Reference answer No.39, seventh grade volume II, chapter 8 proficiency test (1) Reference answer1,1.a2.c3.b4.c5. 1,011.812. Add and subtract, x 13. 1 14. The answer is not unique, such as x+y = 2. 262x-y = 0 three, 17. ( 1)x = 5,{(2)x =- 10,{ y = 1; Y =-25. 18。 We can get the equations 5x+2y = 1, {x = 1, {and then substitute x = 1, y =-2 into the equation (k- 1) x+ky. Get k- 1-2k = 3. Get KX+Y =- 1. Y =-2。 =-4. 19. Let apples be X yuan per kilogram and bananas be Y yuan per kilogram. According to the meaning of the question, 3x+2y = 22 is obtained. {The solution is x = 4. Bananas are 5 yuan per kilogram. 2x+5y = 33.y = 5。 4.20. Suppose that there are x million people traveling between the two sides of the strait by plane and y million people traveling between the two sides of the strait by ship every year. According to the meaning of the topic, x+y = 500, which means 4x+22y = 2,900. x = 450. {So, there are 4.5 million people traveling between the two sides of the strait by plane and 500,000 people traveling between the two sides of the strait by ship every year. y = 50.2 1。 (1) According to the meaning of the question, get 10 = 100k+b, {Solve this system of equations and get k =-1. 10 {8 = 120k+b.b = 20。 (2) Substitute k =-1 and b = 20 into y = kx+b to get y =-1x+20. When x = 140, Y =-1× 140+20 = 6. So when the selling price is 140 yuan 10 10/ piece, 6 pieces can be sold every day. Grade 7 (b) Reference answers to Chapter 8 Level Test in Volume 2 1,1.b2.b3.c4.b5.b6.c7.d8.ax+y =100,2,9. 2, 1 10.3 1 1.5 12.-5 13.3x2- 2x + 1 14.2x - y = 30,{ 15。 { 16.5,443y = 4x-203x +y= 1003x = 0,III。 17.( 1)x = 5,{(2){ y = 5; Y =2.5 18。 Because the solutions of the two equations are the same, we can get the equations 2x+5y =-6, where {x = 2 is the solution and 3x-5y = 16. y =-2。 A represents the other two equations. {the solution is a = 1, {- a+b =-4.b =-3. When a = 1 and b =-3, (2a+b) 201= (2×1-3) 201=-/kloc-0. Setting up 1 notebook requires X yuan. 1 notebook needs 2 yuan, 1 pen needs 4 yuan. x+4y = 18.y = 4。 Four. 20.( 1) suppose x workers are arranged to make shirts and y workers to make pants. According to the meaning of the question, x+y = 24, {we should arrange 15 workers to make 3x = 5y.y = 9. We should arrange nine workers to make shirts. (2) Suppose we need to arrange for worker A to make shirts and worker B to make pants. According to the meaning of the question, we get a+b = 24, {a = 18, {so we need to arrange 65438. Arrange six workers to make pants. 30× 3a+ 16× 5b = 2 100。 B = 6.2 1。 (1) There are *** x classmates in the spring outing. Originally planned to rent 45 buses Y, according to the meaning of the question, they got 45Y+. 60(y- 1) = x.y = 5。 There are 240 students, and it was originally planned to rent five 45-seat buses. (2) If only 45 buses are rented: 240 ≈ 45 ≈ 5.3, you need to rent 6 buses. The rent is 220× 6 = 1, 320 yuan. If only 60 buses are rented: 240 ÷ 60 = 4, then we need to rent 4 buses, and the rent is 300× 4 = 1, 200 yuan. Because 1, 200
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