One day, Xiaohong and Xiaoli used the temperature difference to measure the height of the mountain. Xiaohong measured the temperature at the top of the mountain to be - 4 ℃, and Xiaoli measured the temperature at the foot of the mountain to be 6 ℃. It is known that every 100 meters increase in the height of the area, the temperature will decrease by about 0.8 ℃, and the height of the mountain is about 10 ℃______ Rice

One day, Xiaohong and Xiaoli used the temperature difference to measure the height of the mountain. Xiaohong measured the temperature at the top of the mountain to be - 4 ℃, and Xiaoli measured the temperature at the foot of the mountain to be 6 ℃. It is known that every 100 meters increase in the height of the area, the temperature will decrease by about 0.8 ℃, and the height of the mountain is about 10 ℃______ Rice

According to the meaning of the question, the height of the peak is about 1250 meters
Xiao Hong and Xiao Li went to the bookstore to buy a book with a total of 140 yuan, of which the amount of money Xiao Hong took was 3 / 4 of Xiao Li's?
If the price is less than 3 yuan, the price will be less than 4 yuan
7/4x=140
x=80
That is, Xiao Li took 80, Xiao Hong took 60
Xiaohong and Xiaoli go to the bookstore to buy books. The company takes 140 yuan, of which the amount of money Xiaohong takes is 3 / 4 of Xiaoli's?
Child, you are 6 years old, I will see whether you like to listen to a word, everything depends on yourself, come on!
Xiao Hong brought 60 yuan and Xiao Li 80 yuan.
Xiao Hong brought 60 yuan and Xiao Li 80 yuan
The sum of {a 1 + S 2} is known, and the first term is a n = 0
3(a1+a3)/2+5(a1+a5)/2=50
3(2a1+2d)/2+5(2a1+4d)/2=50
8a1+13d=50
a1a13=a4a4
a1(a1+12d)=(a1+3d)^2
12a1d=9d^2
a1=3/2d
25d=50
D=2
a1=3
an=3+2(n-1)=2n+1
Second grade physics electrothermal experiment
According to the scheme shown in the figure [A and B are connected in series in the circuit, and a match is clamped on each side of a and b], a student explores the relationship between the heat generated by the resistance wire and the size of the resistance. After repeated experiments, it is found that two matches almost burn at the same time
Q: why is there a difference between the experimental results and the conjecture? How to improve the experimental scheme?
I think since this experiment is taken from the same section of electric furnace wire, the material and cross-sectional area of a and B must be the same, the series current is the same, and the default power on time is the same, so the variable should be controlled on the resistance
Is the match burning too low?
To explain the reason, the experts should go in and out
It's interception
It's not a block
This experiment studies the heat generated by the whole resistance wire a and the whole resistance wire B. the match reflects the heat generated by a small part of the resistance wire in contact with the head of the match. Originally, the difference between the heat generated by the whole resistance wire a and B is not much. Each of them only contacts a small part of the resistance wire. Of course, the difference is not much,
The low ignition point of matches has a certain influence, but it is not the main reason. Matches need little heat to burn, so the difference is small.
If the same amount of water is heated by resistance wires at both ends, the respective temperatures are measured by thermometer after the same time,
There is also the greater the difference between the length of the two resistance wires, the more obvious the phenomenon. What is the main reason? How to describe it? [well, I don't think the factor of the length difference of the resistance wire should be considered in this experiment, because when the resistance wire is intercepted, it is possible to leave a large section and a small section. In a word, I don't think it's caused by the unobvious variables
The low ignition point of matches has a certain influence, but it is not the main reason. Matches need little heat to burn, so the difference is small.
If the same amount of water is heated by resistance wires at both ends, the respective temperatures are measured by thermometer after the same time,
There is also the greater the difference between the length of the two resistance wires, the more obvious the phenomenon. Question: what is the main reason? How to describe it? [well, I don't think the factor of the length difference of the resistance wire should be considered in this experiment, because when the resistance wire is intercepted, it is possible to leave a large section and a small section. In a word, I don't think it's caused by the unobvious variables
100 oral arithmetic questions in sixth grade volume 1
The faster you add more!
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...
If A6 = S3 = 12, find the tolerance D and the general formula an
s3=a1+a2+a3=3a1+3d=12
a1+d=4
a6=a1+5d=12
4d=8
D=2
an=a1+2(n-1)
Calculation of electric work and power
1. There are two bulbs. A: "220 v-100 W", B: "220 v-40 W"
(1) Which one is on?
(2) What is the resistance of the two filaments under normal illumination? If the material and length of the two filaments are the same, which filament is thin?
(3) What is the current of normal illumination?
(4) How many joules of heat is produced in half a minute when a lamp is normally on?
(5) How many hours can one kilowatt hour power supply supply a lamp to work normally?
(6) If it is connected to the high power circuit of 110V and 110V?
(7) If a lamp is connected to a certain circuit and the actual current is 0.3A, what is the actual power of a lamp?
(8) If the a lamp is connected to the 380V circuit, how large a protection resistor should be connected in series?
(9) Which lamp is on in series? Which lamp is on in parallel?
(10) When two lamps are connected in series, if only one lamp lights normally, what is the voltage at both ends of the circuit?
(11) The two lamps are connected in series with a 220 V power supply. Which lamp is on? What is the actual power?
(12) After two lamps are connected in parallel to the home circuit, which lamp is on? What is the power?
(1) P a = 100W, P B = 40W, because p a > P B, so a lamp is on (2), r a = u ^ 2 / p a = (220 V) ^ 2 / 100 W = 484 Ω, R B = u ^ 2 / P B = (220 V) ^ 2 / 40 W = 1210 Ω, if the material and length of the two filaments are the same, the filament of B lamp is thin (3)
Ask one by one!
1.100w bright
2.100w48.88 Ω 40w1.21 Ω.100w
3.100W0.45A 40W0.18A
4.360J
5.10 hours
6. The resistance is constant, and the voltage is proportional to the current. 24.75w
7.66W
438 Euro
9. Two lights in series 40W on, parallel 100W on
10.110V
40 W
12.40w bright. 100W 40W
1. A light 2, a 484 Euro B 1210 Euro 3, a 0.45 a B 0.18 a 4, 3000 coke 5, 10 hours 6, 25 Watt 7, 43.56 watt 8, 355.6 Euro 9, Series B light on, parallel a light on. 10. 308v, 11, B light on. 12. The first light is on
About fractions
5/6+1/6 5/6-6/2 7/3-4/3 7/4+2/1 5/9+5/8 1/3+5/6 7/6+6/9 1/2+1/3 2/1-5/4 3/4+5/44/5+6/5 5/6+6/7 1/7×1/5 1/2×1/5 5/6-1/21/2×3/5 30×1/3 2/3×12 3/5×5/6 2/5×1/3 1/2-1/6 5/16-5/8 1/3+1/63 1/3+1/35 1/3+1/995/6+7/12 9/20+4/5 9/20+1/2 7/12+1/2 11/30+1/310/42+6/7 15/56+7/8 5/6+1/3 5/6+1/4 7/12+1/41/4+1/5 5×1/5 2×3/10 30×1/2 1×1/21/2×3 1/3×4 1/4×5 1/5×6 1/6×71/7×8 1/8×9 1/9×10 1/5-1/9 1/2-1/31/3-1/4 1/4-1/5 1/5-1/6 1/6-1/7 1/7-1/8 1/8-1/9 1/9-1/10 1/3+1/4 1/5+1/6 1/7+1/8
/It's a division sign
This one has answers
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
Maybe it's a little simple. Let's see
It is known that the sum of the first n terms of the arithmetic sequence {an} with non-zero tolerance is Sn, S3 = A4 + 6, and A1, A4, A13 are equal proportion sequence. (I) find the general term formula of the sequence {an}; (II) find the sum of the first n terms of the sequence {1sn}
(I) let the tolerance be D, and D ≠ 0, ∵ S3 = A4 + 6, and A1, A4, A13 be equal proportion sequence ∵ 3A1 + 3D = a1 + 3D + 6, (a1 + 3D) 2 = A1 (a1 + 12D) ∵ A1 = 3, d = 2 ∵ an = 3 + 2 (n-1) = 2n + 1; (II) Sn = n (3 + 2n + 1) 2 = n (n + 2), ∵ 1sn = 1n (n + 2) = 12 (1n-1n + 2) ∵ the sum of the first n terms of sequence {1sn} is 12 (1-13 + 12-14 + 13-15 + +1n-1n+2)=12(1+12-1n+1-1n+2)=3n2+5n4(n+1)(n+2)．