4. Solutions; There are x people in the first prize, 200x +50(22-x )=2000, and x =6.
5. Solution: (1) is not unique; (2) At least 1 1 and at most 15.
Do winter vacation homework easily every day (2)
1, D 2, D 3, B 4, 70 yuan 5, 3a 6, 150 degrees 7, 144 degrees.
8. Solution: Let the deposit x yuan x+ x*3%*3=2 180, x=2000.
14, solution: let B catch up with A in x minutes, 180x-80x=400 x=4, A leaves the exhibition hall 1000-720=280m.
Winter vacation homework (3) the answer:
1.C
2.B
3.B
4.A
5.D
6.0.5 -2 0.5
7. 10 15 7
8. 1 2
9. Big ones
10.X=- 25/ 14
1 1. Original formula =mn, when, original formula =-2.
12.200 yuan
Do winter vacation homework easily every day (4)
1.C
2.A
3.D
4.D
5.9/25, 1 1/36,
6.m=- 1
7. 10.5 days
8.( 1) The sum of five numbers is five times that of the middle number; (2)5x； (3) No, because if the sum of five numbers is equal to 20 10, the middle number is 402, and 402 is in the first column, so it is impossible to frame such five numbers.
Do winter vacation homework easily every day (5)
1.D
2.C
3.C
4.πd，πd2/4，4πd/3，πd/3
5.5(-P+q)
6.20x+ 10y
7. 1.0 18a
8.( 1)6x2y-7x2y(2)5x2-xy-y2
9.( 1)(x- 12)/8 = x/9+2(2)8y+ 12 = 9(y-2)
10. 2 vehicles for the first team and 28 vehicles for the second team.
1 1.( 1) (2)34℃
Do winter vacation homework easily every day (6)
1.D
2.B
3.B
4.C
5.-0.8
6.9 >
7.227/ 15
8.- 1 1
9. The original formula = -2(a+b)2,-118.
10.∠2=60
Do winter vacation homework easily every day (7)
1. 15/4; -4/ 15 ; 2.2.0577ⅹ 108; 3 . B2-2 b+ 1； 4. 1/9 ; 5.6,4;
6.55 ; 7.B 8。 C 9。 D 10。 ①-4x+2y； ② 2x2-y2
1 1.①x =-3； ②x = 7 12.56；
Do winter vacation homework easily every day (8)
1.-5/8; 1 2.2 a2； 5ab 3.4a 2-ab； -2 a2-3ab；
4.(5n+3) 9。 A 10。 C
12. 1)35km； 2)5.85 liters
Do winter vacation homework easily every day (9)
1.m=4
2.a= 1
3. 1 12? 27′ 5 1? 55′ 73.38?
4.B
5.A
6.D
7.A
8.-7/8 7
9. Omit
10.( 1) 1+24 2+24 22+24 23+24 15 18 20 24 (2)48
Do winter vacation homework easily every day (10).
1.0 2a 2.0 -8 3.3 4.20 5。 D
6.C 7。 C 8。 C 9。 C 10。 A 1 1。 C
12.x=3，x =-38 13. 160h = 15a+ 100 250
Do winter vacation homework easily every day (1 1).
1.5/2，-2/5，5/2 3.6.4* 106 4.70 5.3a
6.90 degrees 7.c8.d9.b10.d11. ( 1)-2
(2)- 13/ 12 12.3 x2-5，7 13。 ( 1)x = 1/2(2)x = 3/ 1 1
Do winter vacation homework easily every day (12).
1， 1.62* 108 2，(3P- 12) 3，D 4，(3)(4)(2)( 1) 5，90 6，7.5cm
7. (1) A:10+1.2 (20-3) = 30.4 Yuan B: 8+1.4 (20-3) = 31.8 yuan A is economical.
(2)A: 10+ 1.2(x-3)= 1.2x+6.4 B:8+ 1.4(x-3)= 1.4x+3.8
A-B = (1.2x+6.4)-(1.4x+3.8) = -0.2x+2.6, and the price difference is (-0.2x+2.6) yuan.
So when x= 13, A=B, when x >；; 13, a is economical, when x
18( 1)& lt； ,<,>, & gt(2) When n= 1, 2, NN+ 1
(3)2007-2008 > 2008-2007;
Do winter vacation homework easily every day (13).
1。 1, 2.-4 or 23. It was 23: 30 the day before. 4. Both are 45.
5. 1 or 4 or 66.64 (-2) 2005 7.b8.d9.b
10.7 1 1 . n/(n+ 1)
Do winter vacation homework easily every day (14).
1.2005 2.& gt3.5x 4-8 5.6 . 543× 107 6。 cone
7. Two points determine a straight line 8.229.10510.d11.c.
12.c 13。 (1) a+2.4 (2) 3,7,2.2 (3) omitted.
Do winter vacation homework easily every day (15).
1、 16 2、0 3、< < 4、 1.5× 108
5, cylinder, cone 6, ∠AOB, ∠AOC, ∠COB, 7, the shortest line segment between two points.
8、 150 9、250 10、2000 1 1、350
Do winter vacation homework easily every day (16).
1、D 2、C 3、C 4、A 5 、( 1)-24 (2)39
6、( 1)3×2 1+2 (2) 12÷3 ×(7- 1)
Do winter vacation homework easily every day (17).
1.C 2。 C 3。 A 4。 Answer 5.45, 0.75 6.
7.44442222、66666×66667
8.-1,-169. (1)164, (2) No danger140 > 132
Do winter vacation homework easily every day (18).
1.-56 2.0 3.4.C 5。 A six. C
7.& gt、& lt、& lt、gt； 、=、gt； 8.8、 10、2n+4
9.n-2、n- 1、n
I don't know if it is