Some positive and negative math problems for me Is zero a non negative number? 2. The meaning of going north - 20 meters is () 3. The smallest positive integer is () and the largest negative integer is () The smallest nonnegative integer is (), and the largest nonpositive integer is () Is "2" the right number 5. The perimeter of the campus was measured by the mathematics interest group. The data of each measurement were 2503m, 2498m, 2502m and 2497m (1) Find the average of the four measurements (2) Based on the average value, the difference between the measured value and the average value is expressed by positive and negative numbers

Some positive and negative math problems for me Is zero a non negative number? 2. The meaning of going north - 20 meters is () 3. The smallest positive integer is () and the largest negative integer is () The smallest nonnegative integer is (), and the largest nonpositive integer is () Is "2" the right number 5. The perimeter of the campus was measured by the mathematics interest group. The data of each measurement were 2503m, 2498m, 2502m and 2497m (1) Find the average of the four measurements (2) Based on the average value, the difference between the measured value and the average value is expressed by positive and negative numbers

1. Is zero a non negative number? Yes. 2. The meaning of - 20 meters to the north is (- 20). 3. The smallest positive integer is (1), the largest negative integer is (- 1). The smallest non negative integer is (0), and the largest non positive integer is (0). 4. Judge whether "2 is a rational number" is correct. (x) 5
yes
20 meters east
1 -1
Yes
-0-:2500
+3 -2 +2 -3
All right~^^
How many jin is this?
Overall parameters: 36cm × 23cm × 5.5cm weight: 2.8kg ± 0.2kg
2.8 * 2 = 5.6 (kg)
What is the conducting current and the maximum power of a 100 meter long copper conductor with a cross-sectional area of 1.5 square mm?
10 meters distance, 1.5 square millimeter wire can pass 10A current, single-phase load 2kW, three-phase load 5kW. 30 meters distance, 1.5 square millimeter wire can pass 8A current, single-phase load 1.6kw, three-phase load 4kw. 60 meters distance, 1.5 square millimeter wire can pass 6A current, single-phase load 1.2kW, three-phase load 3KW
Math problems (positive and negative)
Water level:
Yichang 45.46 Shashi: 37.97 Hankou 23.62 Jiujiang 17.75 Datong 11.92 Chenglingji 30.15 unit M
Taking the average water level as the standard, the water levels of these ports are expressed with positive and negative numbers
Average water level: (45.46 + 37.97 + 23.62 + 17.75 + 11.92 + 30.15) / 6 = 27.81m
Yichang: 45.46-27.81 = 17.65m
Shashi: 37.97-27.81 = 10.16m
Hankou: 23.62-27.81 = -4.19m
Jiujiang: 17.75-27.81 = -10.06m
Datong: 11.92-27.81 = -15.89m
Chenglingji: 30.15-27.81 = 2.34M
I wonder if it's right?
Average first
（45.46+37.97+23.62+17.75+11.92+30.15）/6=27.81
Yichang: 45.46-27.81 = 17.95
Shashi: 37.97-27.81 = 10.16
Hankou: 23.62-27.81 = -4.19
Jiujiang: 17.75-27.81 = -10.06
Datong: 11.92-27.81 = -15.89
Chenglingji: 30.15-27.81 = 2.34
How many grams is one Jin equal to
500 g
10KV overhead power line, conductor lgj-120 / 25, the length of the line is 3km, the load is 1.2MW, the power factor is 0.8, the voltage loss of the line is?
Conductor Impedance x = 0.4k Ω / km r = 0.27k Ω / km
The impedance of the wrong wire above is x = 0.4 Ω / km and R = 0.27 Ω / km
10000 ∑ 58 № 3 ∮ 0.4k no need to thank one two three one two three one two three one two three one two three one two
16-47 28-（-74）
（3.8）-（+7） （-5.9）—（6．1）
（＋2／5）－（－3/5）　　　（－2／5）—（－3／5）
　1／2－1／3　　　　　　　　（－1／2）－1／3
　－4．2＋5．7－8．4＋10　　　－1／4＋5／6＋2／3＋1／2
　12－（－18）＋（－7）－15　　　　　4．7－（8．9）－7．5＋（－6）
Mathematical rational number addition and subtraction process and the answer must have
16-47=-31
28-（-74）=28+74=102
（3.8）-（+7） =3.8-7=-3.2
（-5.9）—（6．1）=-5.9-6.1=-12
（＋2／5）－（－3/5）=2/5+3/5=1
（－2／5）—（－3／5）=-2/5+3/5=1/5
　1／2－1／3　=1/6
（－1／2）－1／3=－1／2－1／3=-5/6
－4．2＋5．7－8．4＋10=5.7-4.2-8.4+10=1.5-8.4+10=10+1.5-8.4=3.1
－1／4＋5／6＋2／3＋1／2=5／6＋2／3＋1／2-1/4=5／6＋2／3＋(1／2-1/4)=3/2+1/4=7/4
12－（－18）＋（－7）－15=12+18-7-15=30-7-15=8
4.7 - (8.9) - 7.5 + (- 6) = 4.7-8.9-7.5-6 = - 17.7
I want questions like this. (- 23) - (- 27) (- 27) can be longer than 1025 - (- 12) (- 1031) = 6 154212 - (- 15) = 381 - 214 545 (- 245) = 86 459 546 4465
16-47=-31
28-（-74）=28+74=102
（3.8）-（+7） =3.8-7=-3.2
（-5.9）—（6．1）=-5.9-6.1=-12
（＋2／5）－（－3/5）=2/5+3/5=1
（－2／5）—（－3／5）=-2/5+3/5=1/5
　1／2－1／3　=1/6
（－1／2）－1／3=－1／2－1／3=-5/6
... unfold
16-47=-31
28-（-74）=28+74=102
（3.8）-（+7） =3.8-7=-3.2
（-5.9）—（6．1）=-5.9-6.1=-12
（＋2／5）－（－3/5）=2/5+3/5=1
（－2／5）—（－3／5）=-2/5+3/5=1/5
　1／2－1／3　=1/6
（－1／2）－1／3=－1／2－1／3=-5/6
－4．2＋5．7－8．4＋10=5.7-4.2-8.4+10=1.5-8.4+10=10+1.5-8.4=3.1
－1／4＋5／6＋2／3＋1／2=5／6＋2／3＋1／2-1/4=5／6＋2／3＋(1／2-1/4)=3/2+1/4=7/4
12－（－18）＋（－7）－15=12+18-7-15=30-7-15=8
4.7 - (8.9) - 7.5 + (- 6) = 4.7-8.9-7.5-6 = - 17.7 (fold up)
16-47=-31
28-（-74）=28+74=102
（3.8）-（+7） =3.8-7=-3.2
（-5.9）—（6．1）=-5.9-6.1=-12
（＋2／5）－（－3/5）=2/5+3/5=1
（－2／5）—（－3／5）=-2/5+3/5=1/5
　1／2－1／3　=1/6
（－1／2）－1／3=－1／2－1／3=-5/6
... unfold
16-47=-31
28-（-74）=28+74=102
（3.8）-（+7） =3.8-7=-3.2
（-5.9）—（6．1）=-5.9-6.1=-12
（＋2／5）－（－3/5）=2/5+3/5=1
（－2／5）—（－3／5）=-2/5+3/5=1/5
　1／2－1／3　=1/6
（－1／2）－1／3=－1／2－1／3=-5/6
－4．2＋5．7－8．4＋10=5.7-4.2-8.4+10=1.5-8.4+10=10+1.5-8.4=3.1
－1／4＋5／6＋2／3＋1／2=5／6＋2／3＋1／2-1/4=5／6＋2／3＋(1／2-1/4)=3/2+1/4=7/4
12－（－18）＋（－7）－15=12+18-7-15=30-7-15=8
4.7 - (8.9) - 7.5 + (- 6) = 4.7-8.9-7.5-6 = - 17.7
How many kilowatt hours is one watt?
How to convert this?
They are units of work that cannot be converted to each other
If we multiply the power by another time, then the result is work. The unit of work is Joule and kilowatt hour. Kilowatt hour is usually called "degree". The relationship between them is as follows:
1 J = 1 W · s
1 kwh = 1 kW · H = 1000 W · H = 1000 * 3600 w · s = 3600000 joules
Namely:
1J=1W·s
1kWh=1kW·h=1000w·h=1000*3600w·s=3600000J
The conductor of a 10KV overhead power line is lgj-150 / 25, the length of the line is 6km, the load of the line is 1.6MW, and the power factor is 0.8
Try to be specific in the process, and add process to the formula,
Since it is an overhead line, only the line resistance and inductive reactance should be considered
The percentage value of pressure drop at the nth load point is calculated as follows:
△Un%=△Un-1%+（PnR+QnX）/10U²,
Where: △ UN% - the pressure drop percentage of the nth point of charge relative to the origin
Δ un-1% - the percentage of pressure drop at the n-1st load point relative to the origin
PN, QN reactive power and active power of the nth load point
R. X-resistance and impedance of the nth load point relative to the origin
Two plus two-thirds is the power of two multiplied by two-thirds, three plus three eighths is the power of three multiplied by three eighths, four plus four fifths is the power of four multiplied by four fifths. If a is ten plus four fifths is the power of ten multiplied by a (a, B are positive integers), then what is a + B
10+A/B=10^2*A/B
A=10 B=99 A+B=109