Xiaohong, Xiaohua and Xiaoli go to the bookstore together to buy the same book. If each person buys one book, Xiaohong's difference is 2.4 yuan, Xiaohua's difference is 4.5 yuan, and Xiaoli's difference is 0.5 yuan; If the sum of three people's money is just enough to buy two books, then one book is () yuan, and Xiao Li brings () yuan more than Xiao Hong?

Xiaohong, Xiaohua and Xiaoli go to the bookstore together to buy the same book. If each person buys one book, Xiaohong's difference is 2.4 yuan, Xiaohua's difference is 4.5 yuan, and Xiaoli's difference is 0.5 yuan; If the sum of three people's money is just enough to buy two books, then one book is () yuan, and Xiao Li brings () yuan more than Xiao Hong?

Let a Book X Yuan, then Xiaohong takes (x-2.4) yuan, Xiaohua takes (x-4.5) yuan, and Xiaoli takes (x + 0.5) yuan. (x - 2.4) + (x - 4.5) + (x + 0.5) = 2x3x - 6.4 = 2XX = 6.4 х x-2.4 = 4x + 0.5 = 6.9 х 6.9 - 4 = 2.9 A: a Book 6.4 yuan, Xiaoli takes 2.9 more than Xiaohong
A: one book costs 6.4 yuan, and Xiao Li brings 2.9 yuan more than Xiao Hong???
My father and mother love their work
Both my parents love their work / jobs.
My parents both love their work / jobs.
Both my father and my mother are fond of their jobs.
My parents are both devoted to their work.
My father and the mother all deeply loves their work
Both of my parents love their work/jobs.
Both my parents love their jobs
Electric power, electric power, thermal power, thermal power
Electric work and electric power formula. Thermal work and thermal power formula. Why is there such a difference?
Why? I still don't understand
Because only electric heaters like electric soldering iron can completely convert electric energy into heat energy, and other electrical appliances can not completely convert electric energy into heat energy, but also light energy, mechanical energy, etc., so both formulas can be used for electric heaters, while for other electrical appliances, the amount or speed of energy consumption can only be calculated by the formula of electric work or electric power
100
Don't be the same
2.8×0.4＝ 1.12
14－7.4＝6.6,
1.92÷0.04＝48,
0.32×500＝160,
0.65＋4.35＝ 5
10－5.4＝4.6,
4÷20＝0.2,
3.5×200＝700,
1.5－0.06＝1.44
0.75÷15＝0.05,
0.4×0.8＝0.32,
4×0.25＝1,
0.36＋1.54＝2
1.01×99＝99.99,
420÷35＝12,
25×12＝300,
135÷0.5＝270
3/4 + 1/4 =1,
2 + 4/9 =22/9,
3 - 2/3 =7/3,
3/4 - 1/2= 1/4
1/6 + 1/2 -1/6 =1/2,
7.5-(2.5+3.8)=1.2,
7/8 + 3/8 =5/4
3/10 +1/5 =1/2,
4/5 - 7/10 =1/10,
2 - 1/6 -1/3 =1.5
0.51÷17＝0.03,
32.8＋19＝51.8,
5.2÷1.3＝4,
1.6×0.4＝ 0.64
4.9×0.7＝3.43,
1÷5＝0.2,
6÷12＝0.5,
0.87－0.49＝0.38
1.(1+1/2)(1+1/3)(1+1/4).(1+1/100)
2.(1-1/2)(1-1/3)(1-1/4).(1-1/100)
3.8+2-8+2
4.25*4/25*4
5.7.26-(5.26-1.5)
6.286+198
7.314-202
8.526+301
9.223-99
10.6.25+3.85-2.125+3.875
11.9-2456*21
12.0.5/11.5-4*2.75
13.1/2×3/5
14.3.375+5.75+2.25+6.625
15.1001－9036÷18
16.3.8×5.25+14.5
17.2.1*4.3+5.7*2.1
18.30×1/3
19.102*45-328
20.2/3×12
21.2.8*3.1+17.6/8
22.3/5×5/6
23.(50-12.5)/2.5
24.2/5×1/3
25.6110*47+639
26.1/2-1/6
27.3.5*2.7-52.2/18
28.1/7×1/5
29.3.375*0.97+0.97*6.625
30.25×4/5
31.6.54+2.4+3.46+0.6
32.5/6-1/2
33.95.6*1.8+95.6*8.2
34.1/2×1/5
35.600-420/12
36.344/3.6-5.4*0.25
37.16/2+30/2+90/6
38.3001-1998.
39.5000-105*34
40.0.15/0.25+0.75*1.2
41.(1/2+1/3+1/4)*0.24
42.(25+4)*4
43.300-4263/21
44.0.81/0.25+5.96
45.403÷13×27
46.1.5×4.2－0.75÷0.25
47.3.27×4 +3.27×5.7
48.（1.2+ 1.8）×4.51025－768÷32
49.0.25×80－0.45÷0.9
50.1025－768÷32
51.0.25*2.69*4
52.2348+275*16
53.2/9*15/8-1/12*9/5
54.2.4+2.4*(5.375-3.375)
55.645-45*12
56.0.15+1.2/0.24-0.45
57.3.75-(2.35+0.25/1.25)
58.76*1/4+23*25/100+0.25
59.10-2.87-7.13
60.0.96+9.6*9.9
61.7.5-5.7*1/3
62.12.37-3.25-6.75
63.16*6.8+2.2*16+16
64.401*19+284
65.58.7-16.65/3.7
66.0.4*4.7*2.5+(2.3+5.3)
67.9.31-1.125-7.875
68.640+128*45
69.8.2*1.6-0.336/4.2
70.400*(0.62+0.08)
2/1*2=1
3/1*3=1
3/2*3=2
3/1*6=2
4/3*8=6
5/3*20=12
7/3*14=6
8/7*40=35
4/3*16=12
9/5*27=15
2/1*30=15
12/7*24=14
30/1*30=1
51/9*102=18
19/9*76=36
4/9*8=18
5/8*90=144
99/98*99=98
3/14*6=28
7/1*28=4
10/1*90=9
5/3*105=63
19/7*38=14
5/1*25=5
8/19*16=38
61/60*122=120
7/2*28=8 6/1*48=8
9/7*18=14
25/7*100=28
9/5*81=45 8/9*16=18
2/1*2=1
3/1*3=1
3/2*3=2
3/1*6=2
4/3*8=6
5/3*20=12
7/3*14=6
8/7*40=35
4/3*16=12
9/5*27=15
2/1*30=15
12/7*24=14
30/1*30=1
51/9*102=18
19/9*76=36
4/9*8=18
5/8*90=144
99/98*99=98
3/14*6=28
7/1*28=4
10/1*90=9
5/3*105=63
19/7*38=14
5/1*25=5
8/19*16=38
61/60*122=120
7/2*28=8
6/1*48=8
9/7*18=14
25/7*100=28
9/5*81=45
8/9*16=18
12÷3/5=12×(5/3）
9÷6/7=9×( 7/6 )
30÷5/6=30×（6/5 ）
4×（3/2 ）=4÷2/3
4÷5/7=4×7/5
3÷4/5=3×5/4
24÷7/16=24×（16/7 ）
A÷C/B=A×B/C
4÷4/5=5
6÷3/4=8
10÷2/5=25
18÷4/9=81/2
4×4/5=16/5
6×3/4=18/4
10×2/5=4
18×4/9=8
3÷3/4=4
2÷1/3=6
6÷4/5=15/2
1÷5/7=7/5
3/4÷3=1/4
1/3÷2=1/6
4/5÷6=2/15
5/7÷1=5/7
2/1*2=1
3/1*3=1
3/2*3=2
3/1*6=2
4/3*8=6
5/3*20=12
7/3*14=6
8/7*40=35
4/3*16=12
9/5*27=15
2/1*30=15
12/7*24=14
30/1*30=1
51/9*102=18
19/9*76=36
4/9*8=18
5/8*90=144
99/98*99=98
3/14*6=28
7/1*28=4
10/1*90=9
5/3*105=63
19/7*38=14
5/1*25=5
8/19*16=38
61/60*122=120
7/2*28=8
6/1*48=8
9/7*18=14
25/7*100=28
9/5*81=45
8/9*16=18
Given the tolerance d > 0 of the arithmetic sequence {an}, the sum of the first n terms is Sn, if S3 = 12, and 2A1, A2, 1 + a3 are equal proportion sequence. (1) the general formula of {an}
A2 ^ 2 = 2A1 * (A3 + 1) (a1 + D) ^ 2 = 2A1 * (a1 + D + 1) A1 ^ 2 + 2a1d + D ^ 2 = 2A1 ^ 2 + 2a1d + 2a1a1 ^ 2 + 2a1-d ^ 2 = 0S3 = 3A1 + 3 * 2 * D / 2 = 3A1 + 3D = 12a1 + D = 4D = 4-a1 substitute the above formula to get A1 ^ 2 + 2A1 - (4-a1) ^ 2 = 0a1 ^ 2 + 2a1-16 + 8a1-a1 ^ 2 = 010a1 = 16a1 = 1.6d = 2.4 so an = a1 + (n-1) * D
All calculation formulas of electric power
(1) series circuit P (electric power) U (voltage) I (current) w (electric work) r (resistance) t (time) current is equal everywhere I1 = I2 = I total voltage equals to the sum of voltage at both ends of each electrical appliance u = U1 + U2 total resistance equals to the sum of resistance R = R1 + R2 U1: U2 = R1: R2 total electric work equals to the sum of electric work w = W1 + W2
Exercises of mental arithmetic in Grade 6
Forceval
1\2×8= 1\3×9= 4\9×7= 9\11×8= 3\6×2\9= 5\9×7\2= 1\10×9\4= 23\4×2\6= 76\5×1\38= 87\9×3\19= 15\4×1\3= 56\2×1\8= 2\9×3\18= 1\4×3= 12\13×26= 19\6×3\2= 2\3×7\2= 6\7×14\2= 16\7×21\4= 29\3...
Five hundred and forty-five
Let the sum of the first n terms of the arithmetic sequence {an} be Sn, if A1 = - 11, A4 + A6 = - 6, then when Sn takes the minimum value, n is equal to ()
A. 6B. 7C. 8D. 9
Let the tolerance of the sequence be D, then A4 + A6 = 2A1 + 8D = 2 × (- 11) + 8D = - 6, the solution is d = 2, so Sn = − 11n + n (n − 1) 2 × 2 = N2 − 12n = (n − 6) 2 − 36, so when n = 6, Sn takes the minimum value. Therefore, select a
Electric power formula
Electric power formula:
DC circuit:
The conversion of electric energy into other forms of energy is called electric work, that is, the work done by the electric field force when the charge is moved, a = Pt
Work done by electric field force in unit time p = UI = I ^ 2R = u ^ 2 / R
AC circuit:
In AC circuit, only resistance consumes power, which is called active power P = uicos θ; inductance and capacitor do not consume power, and they exchange energy with power supply, which is called reactive power q = uisin θ
Let s = UI, which is called apparent power, cos θ power factor
S=√(P^2+Q^2)；cosθ=P/S
I want 25 mixed operation problems of grade five in primary school
1. 3/7 × 49/9 - 4/3
2. 8/9 × 15/36 + 1/27
3. 12× 5/6 – 2/9 ×3
4. 8× 5/4 + 1/4
5. 6÷ 3/8 – 3/8 ÷6
6. 4/7 × 5/9 + 3/7 × 5/9
7. 5/2 -（ 3/2 + 4/5 ）
8. 7/8 + （ 1/8 + 1/9 ）
9. 9 × 5/6 + 5/6
10. 3/4 × 8/9 - 1/3
11. 7 × 5/49 + 3/14
12. 6 ×（ 1/2 + 2/3 ）
13. 8 × 4/5 + 8 × 11/5
14. 31 × 5/6 – 5/6
15. 9/7 - （ 2/7 – 10/21 ）
16. 5/9 × 18 – 14 × 2/7
17. 4/5 × 25/16 + 2/3 × 3/4
18. 14 × 8/7 – 5/6 × 12/15
19. 17/32 – 3/4 × 9/24
20. 3 × 2/9 + 1/3
21. 5/7 × 3/25 + 3/7
22. 3/14 ×× 2/3 + 1/6
23. 1/5 × 2/3 + 5/6
24. 9/22 + 1/11 ÷ 1/2
25. 5/3 × 11/5 + 4/3